Hi Jarod,
On Fri, 14 Jan 2011 15:01:09 -0500, Jarod Wilson wrote:
> The current hdpvr code kmalloc's a new buffer for every i2c read and
> write. Rather than do that, lets allocate a buffer in the driver's
> device struct and just use that every time.
>
> The size I've chosen for the buffer is the maximum size I could
> ascertain might be used by either ir-kbd-i2c or lirc_zilog, plus a bit
> of padding (lirc_zilog may use up to 100 bytes on tx, rounded that up
> to 128).
Definitely a good move, as discussed on IRC earlier this week.
> Note that this might also remedy user reports of very sluggish behavior
> of IR receive with hdpvr hardware.
Maybe. But the fact that the Zilog is unresponsive during processing of
sent data certainly contributes to this feeling too.
>
> Reported-by: Jean Delvare <kh...@linux-fr.org>
> Signed-off-by: Jarod Wilson <ja...@redhat.com>
> ---
>
> Nb: This patch was done atop my prior patch 'hdpvr: enable IR part',
> and serves no purpose if that patch isn't applied first.
>
> drivers/media/video/hdpvr/hdpvr-i2c.c | 24 +++++++-----------------
> drivers/media/video/hdpvr/hdpvr.h | 3 +++
> 2 files changed, 10 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/media/video/hdpvr/hdpvr-i2c.c
> b/drivers/media/video/hdpvr/hdpvr-i2c.c
> index c0696c3..7f1a313 100644
> --- a/drivers/media/video/hdpvr/hdpvr-i2c.c
> +++ b/drivers/media/video/hdpvr/hdpvr-i2c.c
> @@ -57,23 +57,18 @@ static int hdpvr_i2c_read(struct hdpvr_device *dev, int
> bus,
> unsigned char addr, char *data, int len)
> {
> int ret;
> - char *buf = kmalloc(len, GFP_KERNEL);
> - if (!buf)
> - return -ENOMEM;
>
> ret = usb_control_msg(dev->udev,
> usb_rcvctrlpipe(dev->udev, 0),
> REQTYPE_I2C_READ, CTRL_READ_REQUEST,
> - (bus << 8) | addr, 0, buf, len, 1000);
> + (bus << 8) | addr, 0, &dev->i2c_buf, len, 1000);
Shouldn't you first ensure that len <= sizeof(dev->i2c_buf)? It should
hopefully always be the case, but... if it isn't, you'll corrupt your
data structure and possibly more.
>
> if (ret == len) {
> - memcpy(data, buf, len);
> + memcpy(data, &dev->i2c_buf, len);
> ret = 0;
> } else if (ret >= 0)
> ret = -EIO;
>
> - kfree(buf);
> -
> return ret;
> }
>
> @@ -81,31 +76,26 @@ static int hdpvr_i2c_write(struct hdpvr_device *dev, int
> bus,
> unsigned char addr, char *data, int len)
> {
> int ret;
> - char *buf = kmalloc(len, GFP_KERNEL);
> - if (!buf)
> - return -ENOMEM;
>
> - memcpy(buf, data, len);
> + memcpy(&dev->i2c_buf, data, len);
Same here.
> ret = usb_control_msg(dev->udev,
> usb_sndctrlpipe(dev->udev, 0),
> REQTYPE_I2C_WRITE, CTRL_WRITE_REQUEST,
> - (bus << 8) | addr, 0, buf, len, 1000);
> + (bus << 8) | addr, 0, &dev->i2c_buf, len, 1000);
>
> if (ret < 0)
> - goto error;
> + return ret;
>
> ret = usb_control_msg(dev->udev,
> usb_rcvctrlpipe(dev->udev, 0),
> REQTYPE_I2C_WRITE_STATT, CTRL_READ_REQUEST,
> - 0, 0, buf, 2, 1000);
> + 0, 0, &dev->i2c_buf, 2, 1000);
>
> - if ((ret == 2) && (buf[1] == (len - 1)))
> + if ((ret == 2) && (dev->i2c_buf[1] == (len - 1)))
> ret = 0;
> else if (ret >= 0)
> ret = -EIO;
>
> -error:
> - kfree(buf);
> return ret;
> }
>
> diff --git a/drivers/media/video/hdpvr/hdpvr.h
> b/drivers/media/video/hdpvr/hdpvr.h
> index 29f7426..ee74e3b 100644
> --- a/drivers/media/video/hdpvr/hdpvr.h
> +++ b/drivers/media/video/hdpvr/hdpvr.h
> @@ -25,6 +25,7 @@
> KERNEL_VERSION(HDPVR_MAJOR_VERSION, HDPVR_MINOR_VERSION, HDPVR_RELEASE)
>
> #define HDPVR_MAX 8
> +#define HDPVR_I2C_MAX_SIZE 128
>
> /* Define these values to match your devices */
> #define HD_PVR_VENDOR_ID 0x2040
> @@ -109,6 +110,8 @@ struct hdpvr_device {
> struct i2c_adapter i2c_adapter;
> /* I2C lock */
> struct mutex i2c_mutex;
> + /* I2C message buffer space */
> + char i2c_buf[HDPVR_I2C_MAX_SIZE];
>
> /* For passing data to ir-kbd-i2c */
> struct IR_i2c_init_data ir_i2c_init_data;
Other than that, it looks pretty good.
--
Jean Delvare
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