RE: [PATCH] dw9714: Initial driver for dw9714 VCM

[Mani, Rajmohan]

Hi All,
Please follow v5 of this patch for the latest and ignore this patch.
Sorry for the noise.

Raj

> -Original Message-
> From: Mani, Rajmohan
> Sent: Thursday, May 25, 2017 6:50 PM
> To: linux-media@vger.kernel.org
> Cc: mche...@kernel.org; hverk...@xs4all.nl; tf...@chromium.org;
> sakari.ai...@iki.fi; s.nawro...@samsung.com; Toivonen, Tuukka
> <tuukka.toivo...@intel.com>; Mani, Rajmohan <rajmohan.m...@intel.com>
> Subject: [PATCH] dw9714: Initial driver for dw9714 VCM
> 
> DW9714 is a 10 bit DAC, designed for linear control of voice coil motor.
> 
> This driver creates a V4L2 subdevice and provides control to set the desired
> focus.
> 
> Signed-off-by: Rajmohan Mani <rajmohan.m...@intel.com>
> ---
>  drivers/media/i2c/Kconfig  |   9 ++
>  drivers/media/i2c/Makefile |   1 +
>  drivers/media/i2c/dw9714.c | 292
> +
>  3 files changed, 302 insertions(+)
>  create mode 100644 drivers/media/i2c/dw9714.c
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig index
> fd181c9..516e2f2 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -300,6 +300,15 @@ config VIDEO_AD5820
> This is a driver for the AD5820 camera lens voice coil.
> It is used for example in Nokia N900 (RX-51).
> 
> +config VIDEO_DW9714
> + tristate "DW9714 lens voice coil support"
> + depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER &&
> VIDEO_V4L2_SUBDEV_API
> + ---help---
> +   This is a driver for the DW9714 camera lens voice coil.
> +   DW9714 is a 10 bit DAC with 120mA output current sink
> +   capability. This is designed for linear control of
> +   voice coil motors, controlled via I2C serial interface.
> +
>  config VIDEO_SAA7110
>   tristate "Philips SAA7110 video decoder"
>   depends on VIDEO_V4L2 && I2C
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile index
> 62323ec..987bd1f 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -21,6 +21,7 @@ obj-$(CONFIG_VIDEO_SAA7127) += saa7127.o
>  obj-$(CONFIG_VIDEO_SAA7185) += saa7185.o
>  obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
>  obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
> +obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
>  obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
>  obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
>  obj-$(CONFIG_VIDEO_ADV7180) += adv7180.o diff --git
> a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c new file mode
> 100644 index 000..22c84de
> --- /dev/null
> +++ b/drivers/media/i2c/dw9714.c
> @@ -0,0 +1,292 @@
> +/*
> + * Copyright (c) 2015--2017 Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version
> + * 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +
> +#define DW9714_NAME  "dw9714"
> +#define DW9714_MAX_FOCUS_POS 1023
> +/*
> + * This acts as the minimum granularity of lens movement.
> + * Keep this value power of 2, so the control steps can be
> + * uniformly adjusted for gradual lens movement, with desired
> + * number of control steps.
> + */
> +#define DW9714_CTRL_STEPS16
> +#define DW9714_CTRL_DELAY_US 1000
> +/*
> + * S[3:2] = 0x00, codes per step for "Linear Slope Control"
> + * S[1:0] = 0x00, step period
> + */
> +#define DW9714_DEFAULT_S 0x0
> +#define DW9714_VAL(data, s) ((data) << 4 | (s))
> +
> +/* dw9714 device structure */
> +struct dw9714_device {
> + struct i2c_client *client;
> + struct v4l2_ctrl_handler ctrls_vcm;
> + struct v4l2_subdev sd;
> + u16 current_val;
> +};
> +
> +static inline struct dw9714_device *to_dw9714_vcm(struct v4l2_ctrl
> +*ctrl) {
> + return container_of(ctrl->handler, struct dw9714_device, ctrls_vcm); }
> +
> +static inline struct dw9714_device *sd_to_dw9714_vcm(struct v4l2_subdev
> +*subdev) {
> + return container_of(subdev, struct dw9714_device, sd); }
> +
> +static int dw9714_i2c_write(struct i2c_client *client, u16 data) {
> + int ret;
> + u16 val = cpu_to_be16(data);
> +
> + ret = i2c_master_send(client, (const char *), sizeof(val));
> + i

[PATCH] dw9714: Initial driver for dw9714 VCM

[Rajmohan Mani]

DW9714 is a 10 bit DAC, designed for linear
control of voice coil motor.

This driver creates a V4L2 subdevice and
provides control to set the desired focus.

Signed-off-by: Rajmohan Mani 
---
 drivers/media/i2c/Kconfig  |   9 ++
 drivers/media/i2c/Makefile |   1 +
 drivers/media/i2c/dw9714.c | 292 +
 3 files changed, 302 insertions(+)
 create mode 100644 drivers/media/i2c/dw9714.c

diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index fd181c9..516e2f2 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -300,6 +300,15 @@ config VIDEO_AD5820
  This is a driver for the AD5820 camera lens voice coil.
  It is used for example in Nokia N900 (RX-51).
 
+config VIDEO_DW9714
+   tristate "DW9714 lens voice coil support"
+   depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER && 
VIDEO_V4L2_SUBDEV_API
+   ---help---
+ This is a driver for the DW9714 camera lens voice coil.
+ DW9714 is a 10 bit DAC with 120mA output current sink
+ capability. This is designed for linear control of
+ voice coil motors, controlled via I2C serial interface.
+
 config VIDEO_SAA7110
tristate "Philips SAA7110 video decoder"
depends on VIDEO_V4L2 && I2C
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index 62323ec..987bd1f 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_VIDEO_SAA7127) += saa7127.o
 obj-$(CONFIG_VIDEO_SAA7185) += saa7185.o
 obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
 obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
+obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
 obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
 obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
 obj-$(CONFIG_VIDEO_ADV7180) += adv7180.o
diff --git a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c
new file mode 100644
index 000..22c84de
--- /dev/null
+++ b/drivers/media/i2c/dw9714.c
@@ -0,0 +1,292 @@
+/*
+ * Copyright (c) 2015--2017 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#define DW9714_NAME"dw9714"
+#define DW9714_MAX_FOCUS_POS   1023
+/*
+ * This acts as the minimum granularity of lens movement.
+ * Keep this value power of 2, so the control steps can be
+ * uniformly adjusted for gradual lens movement, with desired
+ * number of control steps.
+ */
+#define DW9714_CTRL_STEPS  16
+#define DW9714_CTRL_DELAY_US   1000
+/*
+ * S[3:2] = 0x00, codes per step for "Linear Slope Control"
+ * S[1:0] = 0x00, step period
+ */
+#define DW9714_DEFAULT_S 0x0
+#define DW9714_VAL(data, s) ((data) << 4 | (s))
+
+/* dw9714 device structure */
+struct dw9714_device {
+   struct i2c_client *client;
+   struct v4l2_ctrl_handler ctrls_vcm;
+   struct v4l2_subdev sd;
+   u16 current_val;
+};
+
+static inline struct dw9714_device *to_dw9714_vcm(struct v4l2_ctrl *ctrl)
+{
+   return container_of(ctrl->handler, struct dw9714_device, ctrls_vcm);
+}
+
+static inline struct dw9714_device *sd_to_dw9714_vcm(struct v4l2_subdev 
*subdev)
+{
+   return container_of(subdev, struct dw9714_device, sd);
+}
+
+static int dw9714_i2c_write(struct i2c_client *client, u16 data)
+{
+   int ret;
+   u16 val = cpu_to_be16(data);
+
+   ret = i2c_master_send(client, (const char *), sizeof(val));
+   if (ret != sizeof(val)) {
+   dev_err(>dev, "I2C write fail\n");
+   return -EIO;
+   }
+   return 0;
+}
+
+static int dw9714_t_focus_vcm(struct dw9714_device *dw9714_dev, u16 val)
+{
+   struct i2c_client *client = dw9714_dev->client;
+
+   dw9714_dev->current_val = val;
+
+   return dw9714_i2c_write(client, DW9714_VAL(val, DW9714_DEFAULT_S));
+}
+
+static int dw9714_set_ctrl(struct v4l2_ctrl *ctrl)
+{
+   struct dw9714_device *dev_vcm = to_dw9714_vcm(ctrl);
+
+   if (ctrl->id == V4L2_CID_FOCUS_ABSOLUTE)
+   return dw9714_t_focus_vcm(dev_vcm, ctrl->val);
+
+   return -EINVAL;
+}
+
+static const struct v4l2_ctrl_ops dw9714_vcm_ctrl_ops = {
+   .s_ctrl = dw9714_set_ctrl,
+};
+
+static int dw9714_init_controls(struct dw9714_device *dev_vcm)
+{
+   struct v4l2_ctrl_handler *hdl = _vcm->ctrls_vcm;
+   const struct v4l2_ctrl_ops *ops = _vcm_ctrl_ops;
+   struct i2c_client *client = dev_vcm->client;
+
+   v4l2_ctrl_handler_init(hdl, 1);
+
+   v4l2_ctrl_new_std(hdl, ops, V4L2_CID_FOCUS_ABSOLUTE,
+ 0, 

RE: [PATCH] dw9714: Initial driver for dw9714 VCM

[Mani, Rajmohan]

Hi Sakari,
Please see comments inline below.

> -Original Message-
> From: Sakari Ailus [mailto:sakari.ai...@iki.fi]
> Sent: Tuesday, May 09, 2017 4:55 AM
> To: Mani, Rajmohan <rajmohan.m...@intel.com>
> Cc: linux-media@vger.kernel.org; mche...@kernel.org
> Subject: Re: [PATCH] dw9714: Initial driver for dw9714 VCM
> 
> Hi Rajmohan,
> 
> A few comments below...
> 
> On Sun, May 07, 2017 at 04:33:24AM -0700, rajmohan.m...@intel.com
> wrote:
> > From: Rajmohan Mani <rajmohan.m...@intel.com>
> >
> > DW9714 is a 10 bit DAC, designed for linear control of voice coil
> > motor.
> >
> > This driver creates a V4L2 subdevice and provides control to set the
> > desired focus.
> >
> > Signed-off-by: Rajmohan Mani <rajmohan.m...@intel.com>
> > ---
> >  drivers/media/i2c/Kconfig  |   9 ++
> >  drivers/media/i2c/Makefile |   1 +
> >  drivers/media/i2c/dw9714.c | 333
> > +
> >  3 files changed, 343 insertions(+)
> >  create mode 100644 drivers/media/i2c/dw9714.c
> >
> > diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> > index fd181c9..4f0a7ad 100644
> > --- a/drivers/media/i2c/Kconfig
> > +++ b/drivers/media/i2c/Kconfig
> > @@ -300,6 +300,15 @@ config VIDEO_AD5820
> >   This is a driver for the AD5820 camera lens voice coil.
> >   It is used for example in Nokia N900 (RX-51).
> >
> > +config VIDEO_DW9714
> > +   tristate "DW9714 lens voice coil support"
> > +   depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
> 
> You should also depend on VIDEO_V4L2_SUBDEV_API .

Ack

> 
> > +   ---help---
> > + This is a driver for the DW9714 camera lens voice coil.
> > + DW9714 is a 10 bit DAC with 120mA output current sink
> > + capability. This is designed for linear control of
> > + voice coil motors, controlled via I2C serial interface.
> > +
> >  config VIDEO_SAA7110
> > tristate "Philips SAA7110 video decoder"
> > depends on VIDEO_V4L2 && I2C
> > diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> > index 62323ec..987bd1f 100644
> > --- a/drivers/media/i2c/Makefile
> > +++ b/drivers/media/i2c/Makefile
> > @@ -21,6 +21,7 @@ obj-$(CONFIG_VIDEO_SAA7127) += saa7127.o
> >  obj-$(CONFIG_VIDEO_SAA7185) += saa7185.o
> >  obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
> >  obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
> > +obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
> >  obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
> >  obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
> >  obj-$(CONFIG_VIDEO_ADV7180) += adv7180.o diff --git
> > a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c new file
> > mode 100644 index 000..276d3f2
> > --- /dev/null
> > +++ b/drivers/media/i2c/dw9714.c
> > @@ -0,0 +1,333 @@
> > +/*
> > + * Copyright (c) 2015--2017 Intel Corporation.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License
> > +version
> > + * 2 as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + */
> > +
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +
> > +#define DW9714_NAME"dw9714"
> > +#define DW9714_MAX_FOCUS_POS   1023
> > +#define DW9714_CTRL_STEPS  16  /* Keep this value power of 2
> */
> > +#define DW9714_CTRL_DELAY_US   1000
> > +/*
> > + * S[3:2] = 0x00, codes per step for "Linear Slope Control"
> > + * S[1:0] = 0x00, step period
> > + */
> > +#define DW9714_DEFAULT_S 0x0
> > +#define DW9714_VAL(data, s) (u16)((data) << 4 | (s))
> > +
> > +/* dw9714 device structure */
> > +struct dw9714_device {
> > +   struct i2c_client *client;
> > +   struct v4l2_ctrl_handler ctrls_vcm;
> > +   struct v4l2_subdev sd;
> > +   u16 current_val;
> > +};
> > +
> > +#define to_dw9714_vcm(_ctrl)   \
> > +   container_of(_ctrl->handler, struct dw9714_device, ctrls_vcm)
> > +
> > +static int dw9714_i2c_write(struct i2c_client *client, u16 data) {
> > +   const int num_msg = 

Re: [PATCH] dw9714: Initial driver for dw9714 VCM

[Tomasz Figa]

On Tue, May 9, 2017 at 9:22 PM, Tomasz Figa  wrote:
> +Rafael, Kevin and Ulf,
>
> On Tue, May 9, 2017 at 8:16 PM, Sakari Ailus  wrote:
>> Hi Tomasz,
>>
>> On Tue, May 09, 2017 at 07:38:26PM +0800, Tomasz Figa wrote:
>>> On Tue, May 9, 2017 at 6:40 PM, Sakari Ailus  wrote:
>>> > Hi Tomasz,
>>> >
>>> > On Tue, May 09, 2017 at 04:30:40PM +0800, Tomasz Figa wrote:
>>> >> Hi Sakari,
>>> >>
>>> >> On Tue, May 9, 2017 at 4:55 AM, Sakari Ailus  wrote:
>>> >> > Hi Rajmohan,
>>> >> >
>>> >> > A few comments below...
>>> >> >
>>> >> > On Sun, May 07, 2017 at 04:33:24AM -0700, rajmohan.m...@intel.com 
>>> >> > wrote:
>>> >> >> +#ifdef CONFIG_PM
>>> >> >> +
>>> >> >> +static int dw9714_runtime_suspend(struct device *dev)
>>> >> >> +{
>>> >> >> + return 0;
>>> >> >> +}
>>> >> >> +
>>> >> >> +static int dw9714_runtime_resume(struct device *dev)
>>> >> >> +{
>>> >> >> + return 0;
>>> >> >
>>> >> > I think it'd be fine to remove empty callbacks.
>>> >>
>>> >> It's actually a bit more complicated (if a PM domain is attached, the
>>> >> callbacks must be present), however in case of external I2C devices it
>>> >> should be fine indeed. However, AFAIK, pm_runtime_no_callbacks()
>>> >> should be called.
>>> >
>>> > I wonder if I'm missing something --- acpi_subsys_runtime_resume() first
>>> > calls acpi_dev_runtime_resume() and if all goes well, the proceeds to call
>>> > pm_generic_runtime_resume() which calls device's runtime_resume() if it's
>>> > non-NULL.
>>> >
>>> > In other words, having a runtime_resume() and runtime_suspend() callbacks
>>> > that return zero is equivalent of having neither of the callbacks.
>>>
>>> Ah, I missed the fact this device is instantiated by ACPI and it has
>>> different handling of runtime PM, which apparently means it doesn't
>>> use the code paths affected by the PM domain thing I mentioned.
>>
>> I have to admit I'm no expert in the topic but I'd presume that other
>> implementations should still maintain consistent behaviour towards drivers.
>> acpi_subsys_runtime_resume() is the PM domain runtime_resume() callback in
>> acpi_general_pm_domain.
>
> Let's see. For platform bus this seems to be reasonable indeed -
> __rpm_get_callback() will use the callbacks of PM domain, device type,
> device class or device bus, whichever is available first, in this
> order. Looking at platform_bus_type, the equivalent resume callback is
> pm_generic_runtime_resume() and it will indeed silently return 0 if
> there is no dev->pm->runtime_resume.
>
> However for I2C bus, i2c_bus_type doesn't seem to have .pm defined.
> Type and class are device/driver-specific things, so let's assume they
> don't have .pm set. If the driver doesn't have .pm, then the only way
> __rpm_get_callback() can return a non-NULL value is when
> dev->pm_domain is non NULL (which seems to be the ACPI case actually).
> Otherwise, if __rpm_get_callback() returns NULL, pm_runtime_get*()
> will fail with -ENOSYS. This is because rpm_resume() calls
> rpm_callback(callback, dev), where callback is the value returned by
> __rpm_get_callback() and rpm_callback() returns -ENOSYS if callback is
> NULL. This is where pm_runtime_no_callbacks() comes handy, as it
> bypasses the code getting and calling the callback, so it doesn't
> return the error anymore.
>
> There is however the other side of the coin. If
> pm_runtime_no_callbacks() is called, all kind of callbacks are
> bypassed, so even the PM domain code is not invoked. This is kind of
> tricky, because the driver must be now aware of whether it's running
> under a PM domain or not and call this pm_runtime_no_callbacks()
> depending on the outcome, to guarantee correct operation (PM domain
> callbacks must be called, even if device driver doesn't have its
> own)... Which IMHO doesn't make sense.
>
> I guess the correct way to proceed here would be adding .pm ops to
> i2c_bus_type, just as it's done with platform_bus_type.

Ah, sorry, I mean, the correct way to proceed here to make the
behavior consistent. For Raj's patch, since a) the driver needs to
restore the control value and b) it's supposed to be primarily
instantiated by ACPI, we shouldn't hit the above problem for now.

Best regards,
Tomasz

Re: [PATCH] dw9714: Initial driver for dw9714 VCM

[Tomasz Figa]

+Rafael, Kevin and Ulf,

On Tue, May 9, 2017 at 8:16 PM, Sakari Ailus  wrote:
> Hi Tomasz,
>
> On Tue, May 09, 2017 at 07:38:26PM +0800, Tomasz Figa wrote:
>> On Tue, May 9, 2017 at 6:40 PM, Sakari Ailus  wrote:
>> > Hi Tomasz,
>> >
>> > On Tue, May 09, 2017 at 04:30:40PM +0800, Tomasz Figa wrote:
>> >> Hi Sakari,
>> >>
>> >> On Tue, May 9, 2017 at 4:55 AM, Sakari Ailus  wrote:
>> >> > Hi Rajmohan,
>> >> >
>> >> > A few comments below...
>> >> >
>> >> > On Sun, May 07, 2017 at 04:33:24AM -0700, rajmohan.m...@intel.com wrote:
>> >> [snip]
>> >> >> + rval = v4l2_async_register_subdev(_dev->sd);
>> >> >> + if (rval < 0)
>> >> >> + goto err_cleanup;
>> >> >> +
>> >> >> + pm_runtime_enable(>dev);
>> >> >
>> >> > Getting PM runtime right doesn't seem to be easy. :-I
>> >> >
>> >> > pm_runtime_enable() alone doesn't do the trick. I wonder if adding
>> >> > pm_runtime_suspend() would do the trick.
>> >>
>> >> Is this something specific for I2C devices? For platform devices,
>> >> typically pm_runtime_enable() is the only thing you would need to do.
>> >
>> > I think you're right --- driver_probe_device() will call pm_request_idle()
>> > to the device right after probe. So indeed calling pm_runtime_enable() is
>> > enough.
>> >
>> >> >> +
>> >> >> + return 0;
>> >> >> +
>> >> >> +err_cleanup:
>> >> >> + dw9714_subdev_cleanup(dw9714_dev);
>> >> >> + dev_err(>dev, "Probe failed: %d\n", rval);
>> >> >> + return rval;
>> >> >> +}
>> >> >> +
>> >> >> +static int dw9714_remove(struct i2c_client *client)
>> >> >> +{
>> >> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> >> >> + struct dw9714_device *dw9714_dev = container_of(sd,
>> >> >> + struct 
>> >> >> dw9714_device,
>> >> >> + sd);
>> >> >> +
>> >> >> + pm_runtime_disable(>dev);
>> >> >> + dw9714_subdev_cleanup(dw9714_dev);
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +#ifdef CONFIG_PM
>> >> >> +
>> >> >> +static int dw9714_runtime_suspend(struct device *dev)
>> >> >> +{
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int dw9714_runtime_resume(struct device *dev)
>> >> >> +{
>> >> >> + return 0;
>> >> >
>> >> > I think it'd be fine to remove empty callbacks.
>> >>
>> >> It's actually a bit more complicated (if a PM domain is attached, the
>> >> callbacks must be present), however in case of external I2C devices it
>> >> should be fine indeed. However, AFAIK, pm_runtime_no_callbacks()
>> >> should be called.
>> >
>> > I wonder if I'm missing something --- acpi_subsys_runtime_resume() first
>> > calls acpi_dev_runtime_resume() and if all goes well, the proceeds to call
>> > pm_generic_runtime_resume() which calls device's runtime_resume() if it's
>> > non-NULL.
>> >
>> > In other words, having a runtime_resume() and runtime_suspend() callbacks
>> > that return zero is equivalent of having neither of the callbacks.
>>
>> Ah, I missed the fact this device is instantiated by ACPI and it has
>> different handling of runtime PM, which apparently means it doesn't
>> use the code paths affected by the PM domain thing I mentioned.
>
> I have to admit I'm no expert in the topic but I'd presume that other
> implementations should still maintain consistent behaviour towards drivers.
> acpi_subsys_runtime_resume() is the PM domain runtime_resume() callback in
> acpi_general_pm_domain.

Let's see. For platform bus this seems to be reasonable indeed -
__rpm_get_callback() will use the callbacks of PM domain, device type,
device class or device bus, whichever is available first, in this
order. Looking at platform_bus_type, the equivalent resume callback is
pm_generic_runtime_resume() and it will indeed silently return 0 if
there is no dev->pm->runtime_resume.

However for I2C bus, i2c_bus_type doesn't seem to have .pm defined.
Type and class are device/driver-specific things, so let's assume they
don't have .pm set. If the driver doesn't have .pm, then the only way
__rpm_get_callback() can return a non-NULL value is when
dev->pm_domain is non NULL (which seems to be the ACPI case actually).
Otherwise, if __rpm_get_callback() returns NULL, pm_runtime_get*()
will fail with -ENOSYS. This is because rpm_resume() calls
rpm_callback(callback, dev), where callback is the value returned by
__rpm_get_callback() and rpm_callback() returns -ENOSYS if callback is
NULL. This is where pm_runtime_no_callbacks() comes handy, as it
bypasses the code getting and calling the callback, so it doesn't
return the error anymore.

There is however the other side of the coin. If
pm_runtime_no_callbacks() is called, all kind of callbacks are
bypassed, so even the PM domain code is not invoked. This is kind of
tricky, because the driver must be now aware of whether it's running
under a PM domain or not and call this 

Re: [PATCH] dw9714: Initial driver for dw9714 VCM

[Sakari Ailus]

Hi Tomasz,

On Tue, May 09, 2017 at 07:38:26PM +0800, Tomasz Figa wrote:
> On Tue, May 9, 2017 at 6:40 PM, Sakari Ailus  wrote:
> > Hi Tomasz,
> >
> > On Tue, May 09, 2017 at 04:30:40PM +0800, Tomasz Figa wrote:
> >> Hi Sakari,
> >>
> >> On Tue, May 9, 2017 at 4:55 AM, Sakari Ailus  wrote:
> >> > Hi Rajmohan,
> >> >
> >> > A few comments below...
> >> >
> >> > On Sun, May 07, 2017 at 04:33:24AM -0700, rajmohan.m...@intel.com wrote:
> >> [snip]
> >> >> + rval = v4l2_async_register_subdev(_dev->sd);
> >> >> + if (rval < 0)
> >> >> + goto err_cleanup;
> >> >> +
> >> >> + pm_runtime_enable(>dev);
> >> >
> >> > Getting PM runtime right doesn't seem to be easy. :-I
> >> >
> >> > pm_runtime_enable() alone doesn't do the trick. I wonder if adding
> >> > pm_runtime_suspend() would do the trick.
> >>
> >> Is this something specific for I2C devices? For platform devices,
> >> typically pm_runtime_enable() is the only thing you would need to do.
> >
> > I think you're right --- driver_probe_device() will call pm_request_idle()
> > to the device right after probe. So indeed calling pm_runtime_enable() is
> > enough.
> >
> >> >> +
> >> >> + return 0;
> >> >> +
> >> >> +err_cleanup:
> >> >> + dw9714_subdev_cleanup(dw9714_dev);
> >> >> + dev_err(>dev, "Probe failed: %d\n", rval);
> >> >> + return rval;
> >> >> +}
> >> >> +
> >> >> +static int dw9714_remove(struct i2c_client *client)
> >> >> +{
> >> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> >> >> + struct dw9714_device *dw9714_dev = container_of(sd,
> >> >> + struct 
> >> >> dw9714_device,
> >> >> + sd);
> >> >> +
> >> >> + pm_runtime_disable(>dev);
> >> >> + dw9714_subdev_cleanup(dw9714_dev);
> >> >> +
> >> >> + return 0;
> >> >> +}
> >> >> +
> >> >> +#ifdef CONFIG_PM
> >> >> +
> >> >> +static int dw9714_runtime_suspend(struct device *dev)
> >> >> +{
> >> >> + return 0;
> >> >> +}
> >> >> +
> >> >> +static int dw9714_runtime_resume(struct device *dev)
> >> >> +{
> >> >> + return 0;
> >> >
> >> > I think it'd be fine to remove empty callbacks.
> >>
> >> It's actually a bit more complicated (if a PM domain is attached, the
> >> callbacks must be present), however in case of external I2C devices it
> >> should be fine indeed. However, AFAIK, pm_runtime_no_callbacks()
> >> should be called.
> >
> > I wonder if I'm missing something --- acpi_subsys_runtime_resume() first
> > calls acpi_dev_runtime_resume() and if all goes well, the proceeds to call
> > pm_generic_runtime_resume() which calls device's runtime_resume() if it's
> > non-NULL.
> >
> > In other words, having a runtime_resume() and runtime_suspend() callbacks
> > that return zero is equivalent of having neither of the callbacks.
> 
> Ah, I missed the fact this device is instantiated by ACPI and it has
> different handling of runtime PM, which apparently means it doesn't
> use the code paths affected by the PM domain thing I mentioned.

I have to admit I'm no expert in the topic but I'd presume that other
implementations should still maintain consistent behaviour towards drivers.
acpi_subsys_runtime_resume() is the PM domain runtime_resume() callback in
acpi_general_pm_domain.

> 
> >
> >>
> >> >
> >> >> +}
> >> >> +
> >> >> +/* This function sets the vcm position, so it consumes least current */
> >> >> +static int dw9714_suspend(struct device *dev)
> >> >> +{
> >> >> + struct i2c_client *client = to_i2c_client(dev);
> >> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> >> >> + struct dw9714_device *dw9714_dev = container_of(sd,
> >> >> + struct 
> >> >> dw9714_device,
> >> >> + sd);
> >> >> + int ret, val;
> >> >> +
> >> >> + dev_dbg(dev, "%s\n", __func__);
> >> >> +
> >> >> + for (val = dw9714_dev->current_val & ~(DW9714_CTRL_STEPS - 1);
> >> >> +  val >= 0; val -= DW9714_CTRL_STEPS) {
> >> >> + ret = dw9714_i2c_write(client,
> >> >> +DW9714_VAL((u16) val, 
> >> >> DW9714_DEFAULT_S));
> >> >> + if (ret)
> >> >> + dev_err(dev, "%s I2C failure: %d", __func__, ret);
> >> >> + usleep_range(DW9714_CTRL_DELAY_US, DW9714_CTRL_DELAY_US + 
> >> >> 10);
> >> >> + }
> >> >> + return 0;
> >> >> +}
> >> >> +
> >> >> +/*
> >> >> + * This function sets the vcm position, so the focus position is set
> >> >> + * closer to the camera
> >> >> + */
> >> >> +static int dw9714_resume(struct device *dev)
> >> >> +{
> >> >> + struct i2c_client *client = to_i2c_client(dev);
> >> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> >> >> + struct dw9714_device *dw9714_dev = container_of(sd,
> >> >> + 

Re: [PATCH] dw9714: Initial driver for dw9714 VCM

[Tomasz Figa]

On Tue, May 9, 2017 at 6:40 PM, Sakari Ailus  wrote:
> Hi Tomasz,
>
> On Tue, May 09, 2017 at 04:30:40PM +0800, Tomasz Figa wrote:
>> Hi Sakari,
>>
>> On Tue, May 9, 2017 at 4:55 AM, Sakari Ailus  wrote:
>> > Hi Rajmohan,
>> >
>> > A few comments below...
>> >
>> > On Sun, May 07, 2017 at 04:33:24AM -0700, rajmohan.m...@intel.com wrote:
>> [snip]
>> >> + rval = v4l2_async_register_subdev(_dev->sd);
>> >> + if (rval < 0)
>> >> + goto err_cleanup;
>> >> +
>> >> + pm_runtime_enable(>dev);
>> >
>> > Getting PM runtime right doesn't seem to be easy. :-I
>> >
>> > pm_runtime_enable() alone doesn't do the trick. I wonder if adding
>> > pm_runtime_suspend() would do the trick.
>>
>> Is this something specific for I2C devices? For platform devices,
>> typically pm_runtime_enable() is the only thing you would need to do.
>
> I think you're right --- driver_probe_device() will call pm_request_idle()
> to the device right after probe. So indeed calling pm_runtime_enable() is
> enough.
>
>> >> +
>> >> + return 0;
>> >> +
>> >> +err_cleanup:
>> >> + dw9714_subdev_cleanup(dw9714_dev);
>> >> + dev_err(>dev, "Probe failed: %d\n", rval);
>> >> + return rval;
>> >> +}
>> >> +
>> >> +static int dw9714_remove(struct i2c_client *client)
>> >> +{
>> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> >> + struct dw9714_device *dw9714_dev = container_of(sd,
>> >> + struct 
>> >> dw9714_device,
>> >> + sd);
>> >> +
>> >> + pm_runtime_disable(>dev);
>> >> + dw9714_subdev_cleanup(dw9714_dev);
>> >> +
>> >> + return 0;
>> >> +}
>> >> +
>> >> +#ifdef CONFIG_PM
>> >> +
>> >> +static int dw9714_runtime_suspend(struct device *dev)
>> >> +{
>> >> + return 0;
>> >> +}
>> >> +
>> >> +static int dw9714_runtime_resume(struct device *dev)
>> >> +{
>> >> + return 0;
>> >
>> > I think it'd be fine to remove empty callbacks.
>>
>> It's actually a bit more complicated (if a PM domain is attached, the
>> callbacks must be present), however in case of external I2C devices it
>> should be fine indeed. However, AFAIK, pm_runtime_no_callbacks()
>> should be called.
>
> I wonder if I'm missing something --- acpi_subsys_runtime_resume() first
> calls acpi_dev_runtime_resume() and if all goes well, the proceeds to call
> pm_generic_runtime_resume() which calls device's runtime_resume() if it's
> non-NULL.
>
> In other words, having a runtime_resume() and runtime_suspend() callbacks
> that return zero is equivalent of having neither of the callbacks.

Ah, I missed the fact this device is instantiated by ACPI and it has
different handling of runtime PM, which apparently means it doesn't
use the code paths affected by the PM domain thing I mentioned.

>
>>
>> >
>> >> +}
>> >> +
>> >> +/* This function sets the vcm position, so it consumes least current */
>> >> +static int dw9714_suspend(struct device *dev)
>> >> +{
>> >> + struct i2c_client *client = to_i2c_client(dev);
>> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> >> + struct dw9714_device *dw9714_dev = container_of(sd,
>> >> + struct 
>> >> dw9714_device,
>> >> + sd);
>> >> + int ret, val;
>> >> +
>> >> + dev_dbg(dev, "%s\n", __func__);
>> >> +
>> >> + for (val = dw9714_dev->current_val & ~(DW9714_CTRL_STEPS - 1);
>> >> +  val >= 0; val -= DW9714_CTRL_STEPS) {
>> >> + ret = dw9714_i2c_write(client,
>> >> +DW9714_VAL((u16) val, 
>> >> DW9714_DEFAULT_S));
>> >> + if (ret)
>> >> + dev_err(dev, "%s I2C failure: %d", __func__, ret);
>> >> + usleep_range(DW9714_CTRL_DELAY_US, DW9714_CTRL_DELAY_US + 
>> >> 10);
>> >> + }
>> >> + return 0;
>> >> +}
>> >> +
>> >> +/*
>> >> + * This function sets the vcm position, so the focus position is set
>> >> + * closer to the camera
>> >> + */
>> >> +static int dw9714_resume(struct device *dev)
>> >> +{
>> >> + struct i2c_client *client = to_i2c_client(dev);
>> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> >> + struct dw9714_device *dw9714_dev = container_of(sd,
>> >> + struct 
>> >> dw9714_device,
>> >> + sd);
>> >> + int ret, val;
>> >> +
>> >> + dev_dbg(dev, "%s\n", __func__);
>> >> +
>> >> + for (val = dw9714_dev->current_val % DW9714_CTRL_STEPS;
>> >> +  val < dw9714_dev->current_val + DW9714_CTRL_STEPS - 1;
>> >> +  val += DW9714_CTRL_STEPS) {
>> >> + ret = dw9714_i2c_write(client,
>> >> +DW9714_VAL((u16) val, 
>> >> DW9714_DEFAULT_S));
>> >> + if (ret)
>> >> + 

Re: [PATCH] dw9714: Initial driver for dw9714 VCM

[Sakari Ailus]

Hi Tomasz,

On Tue, May 09, 2017 at 04:30:40PM +0800, Tomasz Figa wrote:
> Hi Sakari,
> 
> On Tue, May 9, 2017 at 4:55 AM, Sakari Ailus  wrote:
> > Hi Rajmohan,
> >
> > A few comments below...
> >
> > On Sun, May 07, 2017 at 04:33:24AM -0700, rajmohan.m...@intel.com wrote:
> [snip]
> >> + rval = v4l2_async_register_subdev(_dev->sd);
> >> + if (rval < 0)
> >> + goto err_cleanup;
> >> +
> >> + pm_runtime_enable(>dev);
> >
> > Getting PM runtime right doesn't seem to be easy. :-I
> >
> > pm_runtime_enable() alone doesn't do the trick. I wonder if adding
> > pm_runtime_suspend() would do the trick.
> 
> Is this something specific for I2C devices? For platform devices,
> typically pm_runtime_enable() is the only thing you would need to do.

I think you're right --- driver_probe_device() will call pm_request_idle()
to the device right after probe. So indeed calling pm_runtime_enable() is
enough.

> >> +
> >> + return 0;
> >> +
> >> +err_cleanup:
> >> + dw9714_subdev_cleanup(dw9714_dev);
> >> + dev_err(>dev, "Probe failed: %d\n", rval);
> >> + return rval;
> >> +}
> >> +
> >> +static int dw9714_remove(struct i2c_client *client)
> >> +{
> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> >> + struct dw9714_device *dw9714_dev = container_of(sd,
> >> + struct dw9714_device,
> >> + sd);
> >> +
> >> + pm_runtime_disable(>dev);
> >> + dw9714_subdev_cleanup(dw9714_dev);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +#ifdef CONFIG_PM
> >> +
> >> +static int dw9714_runtime_suspend(struct device *dev)
> >> +{
> >> + return 0;
> >> +}
> >> +
> >> +static int dw9714_runtime_resume(struct device *dev)
> >> +{
> >> + return 0;
> >
> > I think it'd be fine to remove empty callbacks.
> 
> It's actually a bit more complicated (if a PM domain is attached, the
> callbacks must be present), however in case of external I2C devices it
> should be fine indeed. However, AFAIK, pm_runtime_no_callbacks()
> should be called.

I wonder if I'm missing something --- acpi_subsys_runtime_resume() first
calls acpi_dev_runtime_resume() and if all goes well, the proceeds to call
pm_generic_runtime_resume() which calls device's runtime_resume() if it's
non-NULL.

In other words, having a runtime_resume() and runtime_suspend() callbacks
that return zero is equivalent of having neither of the callbacks.

> 
> >
> >> +}
> >> +
> >> +/* This function sets the vcm position, so it consumes least current */
> >> +static int dw9714_suspend(struct device *dev)
> >> +{
> >> + struct i2c_client *client = to_i2c_client(dev);
> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> >> + struct dw9714_device *dw9714_dev = container_of(sd,
> >> + struct dw9714_device,
> >> + sd);
> >> + int ret, val;
> >> +
> >> + dev_dbg(dev, "%s\n", __func__);
> >> +
> >> + for (val = dw9714_dev->current_val & ~(DW9714_CTRL_STEPS - 1);
> >> +  val >= 0; val -= DW9714_CTRL_STEPS) {
> >> + ret = dw9714_i2c_write(client,
> >> +DW9714_VAL((u16) val, 
> >> DW9714_DEFAULT_S));
> >> + if (ret)
> >> + dev_err(dev, "%s I2C failure: %d", __func__, ret);
> >> + usleep_range(DW9714_CTRL_DELAY_US, DW9714_CTRL_DELAY_US + 
> >> 10);
> >> + }
> >> + return 0;
> >> +}
> >> +
> >> +/*
> >> + * This function sets the vcm position, so the focus position is set
> >> + * closer to the camera
> >> + */
> >> +static int dw9714_resume(struct device *dev)
> >> +{
> >> + struct i2c_client *client = to_i2c_client(dev);
> >> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> >> + struct dw9714_device *dw9714_dev = container_of(sd,
> >> + struct dw9714_device,
> >> + sd);
> >> + int ret, val;
> >> +
> >> + dev_dbg(dev, "%s\n", __func__);
> >> +
> >> + for (val = dw9714_dev->current_val % DW9714_CTRL_STEPS;
> >> +  val < dw9714_dev->current_val + DW9714_CTRL_STEPS - 1;
> >> +  val += DW9714_CTRL_STEPS) {
> >> + ret = dw9714_i2c_write(client,
> >> +DW9714_VAL((u16) val, 
> >> DW9714_DEFAULT_S));
> >> + if (ret)
> >> + dev_err(dev, "%s I2C failure: %d", __func__, ret);
> >> + usleep_range(DW9714_CTRL_DELAY_US, DW9714_CTRL_DELAY_US + 
> >> 10);
> >> + }
> >> +
> >> + /* restore v4l2 control values */
> >> + ret = v4l2_ctrl_handler_setup(_dev->ctrls_vcm);
> >
> > Doesn't this need to be done for runtime_resume as well?
> 
> This driver doesn't seem to be doing any physical power off in its
> runtime_suspend and I don't expect an 

Re: [PATCH] dw9714: Initial driver for dw9714 VCM

[Tomasz Figa]

Hi Sakari,

On Tue, May 9, 2017 at 4:55 AM, Sakari Ailus  wrote:
> Hi Rajmohan,
>
> A few comments below...
>
> On Sun, May 07, 2017 at 04:33:24AM -0700, rajmohan.m...@intel.com wrote:
[snip]
>> + rval = v4l2_async_register_subdev(_dev->sd);
>> + if (rval < 0)
>> + goto err_cleanup;
>> +
>> + pm_runtime_enable(>dev);
>
> Getting PM runtime right doesn't seem to be easy. :-I
>
> pm_runtime_enable() alone doesn't do the trick. I wonder if adding
> pm_runtime_suspend() would do the trick.

Is this something specific for I2C devices? For platform devices,
typically pm_runtime_enable() is the only thing you would need to do.

>
>> +
>> + return 0;
>> +
>> +err_cleanup:
>> + dw9714_subdev_cleanup(dw9714_dev);
>> + dev_err(>dev, "Probe failed: %d\n", rval);
>> + return rval;
>> +}
>> +
>> +static int dw9714_remove(struct i2c_client *client)
>> +{
>> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> + struct dw9714_device *dw9714_dev = container_of(sd,
>> + struct dw9714_device,
>> + sd);
>> +
>> + pm_runtime_disable(>dev);
>> + dw9714_subdev_cleanup(dw9714_dev);
>> +
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM
>> +
>> +static int dw9714_runtime_suspend(struct device *dev)
>> +{
>> + return 0;
>> +}
>> +
>> +static int dw9714_runtime_resume(struct device *dev)
>> +{
>> + return 0;
>
> I think it'd be fine to remove empty callbacks.

It's actually a bit more complicated (if a PM domain is attached, the
callbacks must be present), however in case of external I2C devices it
should be fine indeed. However, AFAIK, pm_runtime_no_callbacks()
should be called.

>
>> +}
>> +
>> +/* This function sets the vcm position, so it consumes least current */
>> +static int dw9714_suspend(struct device *dev)
>> +{
>> + struct i2c_client *client = to_i2c_client(dev);
>> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> + struct dw9714_device *dw9714_dev = container_of(sd,
>> + struct dw9714_device,
>> + sd);
>> + int ret, val;
>> +
>> + dev_dbg(dev, "%s\n", __func__);
>> +
>> + for (val = dw9714_dev->current_val & ~(DW9714_CTRL_STEPS - 1);
>> +  val >= 0; val -= DW9714_CTRL_STEPS) {
>> + ret = dw9714_i2c_write(client,
>> +DW9714_VAL((u16) val, 
>> DW9714_DEFAULT_S));
>> + if (ret)
>> + dev_err(dev, "%s I2C failure: %d", __func__, ret);
>> + usleep_range(DW9714_CTRL_DELAY_US, DW9714_CTRL_DELAY_US + 10);
>> + }
>> + return 0;
>> +}
>> +
>> +/*
>> + * This function sets the vcm position, so the focus position is set
>> + * closer to the camera
>> + */
>> +static int dw9714_resume(struct device *dev)
>> +{
>> + struct i2c_client *client = to_i2c_client(dev);
>> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> + struct dw9714_device *dw9714_dev = container_of(sd,
>> + struct dw9714_device,
>> + sd);
>> + int ret, val;
>> +
>> + dev_dbg(dev, "%s\n", __func__);
>> +
>> + for (val = dw9714_dev->current_val % DW9714_CTRL_STEPS;
>> +  val < dw9714_dev->current_val + DW9714_CTRL_STEPS - 1;
>> +  val += DW9714_CTRL_STEPS) {
>> + ret = dw9714_i2c_write(client,
>> +DW9714_VAL((u16) val, 
>> DW9714_DEFAULT_S));
>> + if (ret)
>> + dev_err(dev, "%s I2C failure: %d", __func__, ret);
>> + usleep_range(DW9714_CTRL_DELAY_US, DW9714_CTRL_DELAY_US + 10);
>> + }
>> +
>> + /* restore v4l2 control values */
>> + ret = v4l2_ctrl_handler_setup(_dev->ctrls_vcm);
>
> Doesn't this need to be done for runtime_resume as well?

This driver doesn't seem to be doing any physical power off in its
runtime_suspend and I don't expect an I2C device to be put in a PM
domain, so possibly no need for it.

Best regards,
Tomasz

Re: [PATCH] dw9714: Initial driver for dw9714 VCM

[Sakari Ailus]

Hi Rajmohan,

A few comments below...

On Sun, May 07, 2017 at 04:33:24AM -0700, rajmohan.m...@intel.com wrote:
> From: Rajmohan Mani 
> 
> DW9714 is a 10 bit DAC, designed for linear
> control of voice coil motor.
> 
> This driver creates a V4L2 subdevice and
> provides control to set the desired focus.
> 
> Signed-off-by: Rajmohan Mani 
> ---
>  drivers/media/i2c/Kconfig  |   9 ++
>  drivers/media/i2c/Makefile |   1 +
>  drivers/media/i2c/dw9714.c | 333 
> +
>  3 files changed, 343 insertions(+)
>  create mode 100644 drivers/media/i2c/dw9714.c
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index fd181c9..4f0a7ad 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -300,6 +300,15 @@ config VIDEO_AD5820
> This is a driver for the AD5820 camera lens voice coil.
> It is used for example in Nokia N900 (RX-51).
>  
> +config VIDEO_DW9714
> + tristate "DW9714 lens voice coil support"
> + depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER

You should also depend on VIDEO_V4L2_SUBDEV_API .

> + ---help---
> +   This is a driver for the DW9714 camera lens voice coil.
> +   DW9714 is a 10 bit DAC with 120mA output current sink
> +   capability. This is designed for linear control of
> +   voice coil motors, controlled via I2C serial interface.
> +
>  config VIDEO_SAA7110
>   tristate "Philips SAA7110 video decoder"
>   depends on VIDEO_V4L2 && I2C
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index 62323ec..987bd1f 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -21,6 +21,7 @@ obj-$(CONFIG_VIDEO_SAA7127) += saa7127.o
>  obj-$(CONFIG_VIDEO_SAA7185) += saa7185.o
>  obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
>  obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
> +obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
>  obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
>  obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
>  obj-$(CONFIG_VIDEO_ADV7180) += adv7180.o
> diff --git a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c
> new file mode 100644
> index 000..276d3f2
> --- /dev/null
> +++ b/drivers/media/i2c/dw9714.c
> @@ -0,0 +1,333 @@
> +/*
> + * Copyright (c) 2015--2017 Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version
> + * 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +
> +#define DW9714_NAME  "dw9714"
> +#define DW9714_MAX_FOCUS_POS 1023
> +#define DW9714_CTRL_STEPS16  /* Keep this value power of 2 */
> +#define DW9714_CTRL_DELAY_US 1000
> +/*
> + * S[3:2] = 0x00, codes per step for "Linear Slope Control"
> + * S[1:0] = 0x00, step period
> + */
> +#define DW9714_DEFAULT_S 0x0
> +#define DW9714_VAL(data, s) (u16)((data) << 4 | (s))
> +
> +/* dw9714 device structure */
> +struct dw9714_device {
> + struct i2c_client *client;
> + struct v4l2_ctrl_handler ctrls_vcm;
> + struct v4l2_subdev sd;
> + u16 current_val;
> +};
> +
> +#define to_dw9714_vcm(_ctrl) \
> + container_of(_ctrl->handler, struct dw9714_device, ctrls_vcm)
> +
> +static int dw9714_i2c_write(struct i2c_client *client, u16 data)
> +{
> + const int num_msg = 1;
> + int ret;
> + u16 val = cpu_to_be16(data);
> + struct i2c_msg msg = {
> + .addr = client->addr,
> + .flags = 0,
> + .len = sizeof(val),
> + .buf = (u8 *) ,
> + };
> +
> + ret = i2c_transfer(client->adapter, , num_msg);
> +
> + /*One retry */
> + if (ret != num_msg)
> + ret = i2c_transfer(client->adapter, , num_msg);
> +
> + if (ret != num_msg) {
> + dev_err(>dev, "I2C write fail fail\n");
> + return -EIO;
> + } else {
> + return 0;
> + }
> +}
> +
> +static int dw9714_t_focus_vcm(struct dw9714_device *dw9714_dev, u16 val)
> +{
> + struct i2c_client *client = dw9714_dev->client;
> + int ret = -EINVAL;
> +
> + dev_dbg(>dev, "Setting new value VCM: %d\n", val);
> + dw9714_dev->current_val = val;
> +
> + ret = dw9714_i2c_write(client, DW9714_VAL(val, DW9714_DEFAULT_S));
> + return ret;
> +}
> +
> +static int dw9714_set_ctrl(struct v4l2_ctrl *ctrl)
> +{
> + struct dw9714_device *dev_vcm = to_dw9714_vcm(ctrl);
> +
> + if (ctrl->id == V4L2_CID_FOCUS_ABSOLUTE)
> + return dw9714_t_focus_vcm(dev_vcm, ctrl->val);
> + else
> + return -EINVAL;
> +}
> +
> +static const 

RE: [PATCH] dw9714: Initial driver for dw9714 VCM

[Mani, Rajmohan]

Hi Hans,

Thanks for the quick review. Please see my comments inline...
I will post the new v2 patch soon.

> -Original Message-
> From: Hans Verkuil [mailto:hverk...@xs4all.nl]
> Sent: Monday, May 08, 2017 6:59 PM
> To: Mani, Rajmohan <rajmohan.m...@intel.com>; linux-
> me...@vger.kernel.org; mche...@kernel.org
> Subject: Re: [PATCH] dw9714: Initial driver for dw9714 VCM
> 
> Hi Rajmohan,
> 
> Thanks for the patch!
> 
> A quick code review:
> 
> On 05/07/2017 01:33 PM, rajmohan.m...@intel.com wrote:
> > From: Rajmohan Mani <rajmohan.m...@intel.com>
> >
> > DW9714 is a 10 bit DAC, designed for linear control of voice coil
> > motor.
> >
> > This driver creates a V4L2 subdevice and provides control to set the
> > desired focus.
> >
> > Signed-off-by: Rajmohan Mani <rajmohan.m...@intel.com>
> > ---
> >  drivers/media/i2c/Kconfig  |   9 ++
> >  drivers/media/i2c/Makefile |   1 +
> >  drivers/media/i2c/dw9714.c | 333
> > +
> >  3 files changed, 343 insertions(+)
> >  create mode 100644 drivers/media/i2c/dw9714.c
> >
> > diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> > index fd181c9..4f0a7ad 100644
> > --- a/drivers/media/i2c/Kconfig
> > +++ b/drivers/media/i2c/Kconfig
> > @@ -300,6 +300,15 @@ config VIDEO_AD5820
> >   This is a driver for the AD5820 camera lens voice coil.
> >   It is used for example in Nokia N900 (RX-51).
> >
> > +config VIDEO_DW9714
> > +   tristate "DW9714 lens voice coil support"
> > +   depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
> > +   ---help---
> > + This is a driver for the DW9714 camera lens voice coil.
> > + DW9714 is a 10 bit DAC with 120mA output current sink
> > + capability. This is designed for linear control of
> > + voice coil motors, controlled via I2C serial interface.
> > +
> >  config VIDEO_SAA7110
> > tristate "Philips SAA7110 video decoder"
> > depends on VIDEO_V4L2 && I2C
> > diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> > index 62323ec..987bd1f 100644
> > --- a/drivers/media/i2c/Makefile
> > +++ b/drivers/media/i2c/Makefile
> > @@ -21,6 +21,7 @@ obj-$(CONFIG_VIDEO_SAA7127) += saa7127.o
> >  obj-$(CONFIG_VIDEO_SAA7185) += saa7185.o
> >  obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
> >  obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
> > +obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
> >  obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
> >  obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
> >  obj-$(CONFIG_VIDEO_ADV7180) += adv7180.o diff --git
> > a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c new file
> > mode 100644 index 000..276d3f2
> > --- /dev/null
> > +++ b/drivers/media/i2c/dw9714.c
> > @@ -0,0 +1,333 @@
> > +/*
> > + * Copyright (c) 2015--2017 Intel Corporation.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License
> > +version
> > + * 2 as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + */
> > +
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +
> > +#define DW9714_NAME"dw9714"
> > +#define DW9714_MAX_FOCUS_POS   1023
> > +#define DW9714_CTRL_STEPS  16  /* Keep this value power of 2
> */
> > +#define DW9714_CTRL_DELAY_US   1000
> > +/*
> > + * S[3:2] = 0x00, codes per step for "Linear Slope Control"
> > + * S[1:0] = 0x00, step period
> > + */
> > +#define DW9714_DEFAULT_S 0x0
> > +#define DW9714_VAL(data, s) (u16)((data) << 4 | (s))
> > +
> > +/* dw9714 device structure */
> > +struct dw9714_device {
> > +   struct i2c_client *client;
> > +   struct v4l2_ctrl_handler ctrls_vcm;
> > +   struct v4l2_subdev sd;
> > +   u16 current_val;
> > +};
> > +
> > +#define to_dw9714_vcm(_ctrl)   \
> > +   container_of(_ctrl->handler, struct dw9714_device, ctrls_vcm)
> > +
> > +static int dw9714_i2c_write(struct i2c_client *client, u16 data) {
> > +   

Re: [PATCH] dw9714: Initial driver for dw9714 VCM

[Hans Verkuil]

Hi Rajmohan,

Thanks for the patch!

A quick code review:

On 05/07/2017 01:33 PM, rajmohan.m...@intel.com wrote:
> From: Rajmohan Mani 
> 
> DW9714 is a 10 bit DAC, designed for linear
> control of voice coil motor.
> 
> This driver creates a V4L2 subdevice and
> provides control to set the desired focus.
> 
> Signed-off-by: Rajmohan Mani 
> ---
>  drivers/media/i2c/Kconfig  |   9 ++
>  drivers/media/i2c/Makefile |   1 +
>  drivers/media/i2c/dw9714.c | 333 
> +
>  3 files changed, 343 insertions(+)
>  create mode 100644 drivers/media/i2c/dw9714.c
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index fd181c9..4f0a7ad 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -300,6 +300,15 @@ config VIDEO_AD5820
> This is a driver for the AD5820 camera lens voice coil.
> It is used for example in Nokia N900 (RX-51).
>  
> +config VIDEO_DW9714
> + tristate "DW9714 lens voice coil support"
> + depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
> + ---help---
> +   This is a driver for the DW9714 camera lens voice coil.
> +   DW9714 is a 10 bit DAC with 120mA output current sink
> +   capability. This is designed for linear control of
> +   voice coil motors, controlled via I2C serial interface.
> +
>  config VIDEO_SAA7110
>   tristate "Philips SAA7110 video decoder"
>   depends on VIDEO_V4L2 && I2C
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index 62323ec..987bd1f 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -21,6 +21,7 @@ obj-$(CONFIG_VIDEO_SAA7127) += saa7127.o
>  obj-$(CONFIG_VIDEO_SAA7185) += saa7185.o
>  obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
>  obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
> +obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
>  obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
>  obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
>  obj-$(CONFIG_VIDEO_ADV7180) += adv7180.o
> diff --git a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c
> new file mode 100644
> index 000..276d3f2
> --- /dev/null
> +++ b/drivers/media/i2c/dw9714.c
> @@ -0,0 +1,333 @@
> +/*
> + * Copyright (c) 2015--2017 Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version
> + * 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +
> +#define DW9714_NAME  "dw9714"
> +#define DW9714_MAX_FOCUS_POS 1023
> +#define DW9714_CTRL_STEPS16  /* Keep this value power of 2 */
> +#define DW9714_CTRL_DELAY_US 1000
> +/*
> + * S[3:2] = 0x00, codes per step for "Linear Slope Control"
> + * S[1:0] = 0x00, step period
> + */
> +#define DW9714_DEFAULT_S 0x0
> +#define DW9714_VAL(data, s) (u16)((data) << 4 | (s))
> +
> +/* dw9714 device structure */
> +struct dw9714_device {
> + struct i2c_client *client;
> + struct v4l2_ctrl_handler ctrls_vcm;
> + struct v4l2_subdev sd;
> + u16 current_val;
> +};
> +
> +#define to_dw9714_vcm(_ctrl) \
> + container_of(_ctrl->handler, struct dw9714_device, ctrls_vcm)
> +
> +static int dw9714_i2c_write(struct i2c_client *client, u16 data)
> +{
> + const int num_msg = 1;
> + int ret;
> + u16 val = cpu_to_be16(data);
> + struct i2c_msg msg = {
> + .addr = client->addr,
> + .flags = 0,
> + .len = sizeof(val),
> + .buf = (u8 *) ,
> + };
> +
> + ret = i2c_transfer(client->adapter, , num_msg);
> +
> + /*One retry */
> + if (ret != num_msg)
> + ret = i2c_transfer(client->adapter, , num_msg);
> +
> + if (ret != num_msg) {
> + dev_err(>dev, "I2C write fail fail\n");
> + return -EIO;
> + } else {

No need for the 'else' here, since the 'if' already returns.

> + return 0;
> + }
> +}
> +
> +static int dw9714_t_focus_vcm(struct dw9714_device *dw9714_dev, u16 val)
> +{
> + struct i2c_client *client = dw9714_dev->client;
> + int ret = -EINVAL;
> +
> + dev_dbg(>dev, "Setting new value VCM: %d\n", val);
> + dw9714_dev->current_val = val;
> +
> + ret = dw9714_i2c_write(client, DW9714_VAL(val, DW9714_DEFAULT_S));
> + return ret;

Just do return dw9714_i2c_write(client, DW9714_VAL(val, DW9714_DEFAULT_S));

Thus dropping the 'ret' variable.

> +}
> +
> +static int dw9714_set_ctrl(struct v4l2_ctrl *ctrl)
> +{
> + struct dw9714_device *dev_vcm = to_dw9714_vcm(ctrl);
> +
> + if (ctrl->id == V4L2_CID_FOCUS_ABSOLUTE)
> +   

[PATCH] dw9714: Initial driver for dw9714 VCM

[rajmohan . mani]

From: Rajmohan Mani 

DW9714 is a 10 bit DAC, designed for linear
control of voice coil motor.

This driver creates a V4L2 subdevice and
provides control to set the desired focus.

Signed-off-by: Rajmohan Mani 
---
 drivers/media/i2c/Kconfig  |   9 ++
 drivers/media/i2c/Makefile |   1 +
 drivers/media/i2c/dw9714.c | 333 +
 3 files changed, 343 insertions(+)
 create mode 100644 drivers/media/i2c/dw9714.c

diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index fd181c9..4f0a7ad 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -300,6 +300,15 @@ config VIDEO_AD5820
  This is a driver for the AD5820 camera lens voice coil.
  It is used for example in Nokia N900 (RX-51).
 
+config VIDEO_DW9714
+   tristate "DW9714 lens voice coil support"
+   depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
+   ---help---
+ This is a driver for the DW9714 camera lens voice coil.
+ DW9714 is a 10 bit DAC with 120mA output current sink
+ capability. This is designed for linear control of
+ voice coil motors, controlled via I2C serial interface.
+
 config VIDEO_SAA7110
tristate "Philips SAA7110 video decoder"
depends on VIDEO_V4L2 && I2C
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index 62323ec..987bd1f 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_VIDEO_SAA7127) += saa7127.o
 obj-$(CONFIG_VIDEO_SAA7185) += saa7185.o
 obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
 obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
+obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
 obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
 obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
 obj-$(CONFIG_VIDEO_ADV7180) += adv7180.o
diff --git a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c
new file mode 100644
index 000..276d3f2
--- /dev/null
+++ b/drivers/media/i2c/dw9714.c
@@ -0,0 +1,333 @@
+/*
+ * Copyright (c) 2015--2017 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#define DW9714_NAME"dw9714"
+#define DW9714_MAX_FOCUS_POS   1023
+#define DW9714_CTRL_STEPS  16  /* Keep this value power of 2 */
+#define DW9714_CTRL_DELAY_US   1000
+/*
+ * S[3:2] = 0x00, codes per step for "Linear Slope Control"
+ * S[1:0] = 0x00, step period
+ */
+#define DW9714_DEFAULT_S 0x0
+#define DW9714_VAL(data, s) (u16)((data) << 4 | (s))
+
+/* dw9714 device structure */
+struct dw9714_device {
+   struct i2c_client *client;
+   struct v4l2_ctrl_handler ctrls_vcm;
+   struct v4l2_subdev sd;
+   u16 current_val;
+};
+
+#define to_dw9714_vcm(_ctrl)   \
+   container_of(_ctrl->handler, struct dw9714_device, ctrls_vcm)
+
+static int dw9714_i2c_write(struct i2c_client *client, u16 data)
+{
+   const int num_msg = 1;
+   int ret;
+   u16 val = cpu_to_be16(data);
+   struct i2c_msg msg = {
+   .addr = client->addr,
+   .flags = 0,
+   .len = sizeof(val),
+   .buf = (u8 *) ,
+   };
+
+   ret = i2c_transfer(client->adapter, , num_msg);
+
+   /*One retry */
+   if (ret != num_msg)
+   ret = i2c_transfer(client->adapter, , num_msg);
+
+   if (ret != num_msg) {
+   dev_err(>dev, "I2C write fail fail\n");
+   return -EIO;
+   } else {
+   return 0;
+   }
+}
+
+static int dw9714_t_focus_vcm(struct dw9714_device *dw9714_dev, u16 val)
+{
+   struct i2c_client *client = dw9714_dev->client;
+   int ret = -EINVAL;
+
+   dev_dbg(>dev, "Setting new value VCM: %d\n", val);
+   dw9714_dev->current_val = val;
+
+   ret = dw9714_i2c_write(client, DW9714_VAL(val, DW9714_DEFAULT_S));
+   return ret;
+}
+
+static int dw9714_set_ctrl(struct v4l2_ctrl *ctrl)
+{
+   struct dw9714_device *dev_vcm = to_dw9714_vcm(ctrl);
+
+   if (ctrl->id == V4L2_CID_FOCUS_ABSOLUTE)
+   return dw9714_t_focus_vcm(dev_vcm, ctrl->val);
+   else
+   return -EINVAL;
+}
+
+static const struct v4l2_ctrl_ops dw9714_vcm_ctrl_ops = {
+   .s_ctrl = dw9714_set_ctrl,
+};
+
+static int dw9714_init_controls(struct dw9714_device *dev_vcm)
+{
+   struct v4l2_ctrl_handler *hdl = _vcm->ctrls_vcm;
+   const struct v4l2_ctrl_ops *ops = _vcm_ctrl_ops;
+   struct i2c_client *client = dev_vcm->client;
+
+   v4l2_ctrl_handler_init(hdl,