Re: [PATCH 00/38] Fixes related to incorrect usage of unsigned types
On 09/22/2015 11:13 AM, Andrzej Hajda wrote: On 09/21/2015 03:42 PM, David Howells wrote: Andrzej Hajda <a.hajda-sze3o3uu22jbdgjk7y7...@public.gmane.org> wrote: Semantic patch finds comparisons of types: unsigned < 0 unsigned >= 0 The former is always false, the latter is always true. Such comparisons are useless, so theoretically they could be safely removed, but their presence quite often indicates bugs. Or someone has left them in because they don't matter and there's the possibility that the type being tested might be or become signed under some circumstances. If the comparison is useless, I'd expect the compiler to just discard it - for such cases your patch is pointless. If I have, for example: unsigned x; if (x == 0 || x > 27) give_a_range_error(); I will write this as: unsigned x; if (x <= 0 || x > 27) give_a_range_error(); because it that gives a way to handle x being changed to signed at some point in the future for no cost. In which case, your changing the <= to an == "because the < part of the case is useless" is arguably wrong. This is why I have not checked for such cases - I have skipped checks of type unsigned <= 0 exactly for the reasons above. However I have left two other checks as they seems to me more suspicious - they are always true or false. But as Dmitry and Andrew pointed out Linus have quite strong opinion against removing range checks in such cases as he finds it clearer. I think it applies to patches 29-36. I am not sure about patches 26-28,37. Dropped 30/38 and 31/38 from LED tree then. -- Best Regards, Jacek Anaszewski -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC] adp1653: Add device tree bindings for LED controller
Hi Pavel, Sakari, On 11/19/2014 06:53 PM, Sakari Ailus wrote: Hi Jacek and Pavel, Jacek Anaszewski wrote: Hi Pavel, Sakari, On 11/18/2014 05:51 PM, Pavel Machek wrote: Hi! If the hardware LED changes with one that needs different current, the block for the adp1653 stays the same, but white LED block should be updated with different value. I think that you are talking about sub nodes. Indeed I am leaning towards this type of design. I think I am :-). I agree that flash-timeout should be per led - an array, similarly as in case of iout's. Agreed about per-led, disagreed about the array. As all the fields would need arrays, and as LED system currently does not use arrays for label and linux,default-trigger, I believe we should follow existing design and model it as three devices. (It _is_ physically three devices.) Right, I missed that the leds/common.txt describes child node. I propose following modifications to the binding: Optional properties for child nodes: - iout-mode-led : maximum intensity in microamperes of the LED (torch LED for flash devices) - iout-mode-flash : initial intensity in microamperes of the flash LED; it is required to enable support for the flash led - iout-mode-indicator : initial intensity in microamperes of the indicator LED; it is required to enable support for the indicator led - max-iout-mode-led : maximum intensity in microamperes of the LED (torch LED for flash devices) - max-iout-mode-flash : maximum intensity in microamperes of the flash LED - max-iout-mode-indicator : maximum intensity in microamperes of the indicator LED - flash-timeout :timeout in microseconds after which flash led is turned off Ok, I took a look, and iout is notation I understand, but people may have trouble with and I don't see it used anywhere else. Also... do we need both current and max-current properties? But regulators already have regulator-max-microamp property. So what about: max-microamp : maximum intensity in microamperes of the LED (torch LED for flash devices) max-flash-microamp : initial intensity in microamperes of the flash LED; it is required to enable support for the flash led flash-timeout-microseconds : timeout in microseconds after which flash led is turned off If you had indicator on the same led, I guess indicator-microamp : recommended intensity in microamperes of the LED for indication The value for the indicator is maximum as well, not just a recommendation. ...would do? Ongoing discussion allowed me for taking a look at the indicator issue from different perspective. This is also vital for the issue of whether a v4l2-flash sub-device should be created per device or per sub-led [1]. Currently each sub-led is represented as a separate device tree sub node and the led drivers create separate LED class device for the sub nodes. What this implies is that indicator led also must be represented by the separate LED class device. This is contrary to the way how V4L2 Flash API approaches this issue, as it considers a flash device as a regulator chip driven through a bus. The API allows to set the led in torch or flash mode and implicitly assumes that there can be additional indicator led supported, which can't be turned on separately, but the drivers apply the indicator current to the indicator led when the torch or flash led is activated. The indicator is independent of the flash LED in V4L2 flash API. At least that's how it should be, and in adp1653 the two are independent, but the as3645a can't use indicator with the flash AFAIR. Right. I propose to create separate v4l2-flash device for the indicator led, and treat it as a regular sub-led similarly like it is done in the LED subsystem. LED Flash class driver would only add a flag LED_DEV_CAP_INDICATOR and basing on it the v4l2-flash sub-device would create only V4L2_CID_FLASH_INDICATOR_INTENSITY control for it. There could ba also additional control added: V4L2_CID_FLASH_INDICATOR_PATTERN to support the feature supported by some LED class drivers. Interesting idea. The flash controller is still a single I2C device with common set of faults, for instance. Some devices refuse to work again in case of faults until they are cleared (= read). The V4L2_CID_FLASH_FAULT control should be also supported by the indicator v4l2-flash sub-device then. Could the indicator pattern control be present in the same sub-device? Yes, this was my intention. To conclude - the indicator v4l2-flash sub-device should support up to three controls: - V4L2_CID_FLASH_TORCH_INTENSITY - V4L2_CID_FLASH_FAULT - V4L2_CID_FLASH_INDICATOR_PATTERN (if supported by the LED Flash class driver) V4L2_CID_FLASH_INDICATOR_PATTERN would be a menu control with custom
Re: [RFC] adp1653: Add device tree bindings for LED controller
On 11/19/2014 10:45 AM, Jacek Anaszewski wrote: Hi Pavel, Sakari, On 11/18/2014 05:51 PM, Pavel Machek wrote: Hi! If the hardware LED changes with one that needs different current, the block for the adp1653 stays the same, but white LED block should be updated with different value. I think that you are talking about sub nodes. Indeed I am leaning towards this type of design. I think I am :-). I agree that flash-timeout should be per led - an array, similarly as in case of iout's. Agreed about per-led, disagreed about the array. As all the fields would need arrays, and as LED system currently does not use arrays for label and linux,default-trigger, I believe we should follow existing design and model it as three devices. (It _is_ physically three devices.) Right, I missed that the leds/common.txt describes child node. I propose following modifications to the binding: Optional properties for child nodes: - iout-mode-led : maximum intensity in microamperes of the LED (torch LED for flash devices) - iout-mode-flash : initial intensity in microamperes of the flash LED; it is required to enable support for the flash led - iout-mode-indicator : initial intensity in microamperes of the indicator LED; it is required to enable support for the indicator led - max-iout-mode-led : maximum intensity in microamperes of the LED (torch LED for flash devices) - max-iout-mode-flash : maximum intensity in microamperes of the flash LED - max-iout-mode-indicator : maximum intensity in microamperes of the indicator LED - flash-timeout :timeout in microseconds after which flash led is turned off Ok, I took a look, and iout is notation I understand, but people may have trouble with and I don't see it used anywhere else. Also... do we need both current and max-current properties? But regulators already have regulator-max-microamp property. So what about: max-microamp : maximum intensity in microamperes of the LED (torch LED for flash devices) max-flash-microamp : initial intensity in microamperes of the flash LED; it is required to enable support for the flash led flash-timeout-microseconds : timeout in microseconds after which flash led is turned off If you had indicator on the same led, I guess indicator-microamp : recommended intensity in microamperes of the LED for indication ...would do? Ongoing discussion allowed me for taking a look at the indicator issue from different perspective. This is also vital for the issue of whether a v4l2-flash sub-device should be created per device or per sub-led [1]. Currently each sub-led is represented as a separate device tree sub node and the led drivers create separate LED class device for the sub nodes. What this implies is that indicator led also must be represented by the separate LED class device. This is contrary to the way how V4L2 Flash API approaches this issue, as it considers a flash device as a regulator chip driven through a bus. The API allows to set the led in torch or flash mode and implicitly assumes that there can be additional indicator led supported, which can't be turned on separately, but the drivers apply the indicator current to the indicator led when the torch or flash led is activated. I propose to create separate v4l2-flash device for the indicator led, and treat it as a regular sub-led similarly like it is done in the LED subsystem. LED Flash class driver would only add a flag LED_DEV_CAP_INDICATOR and basing on it the v4l2-flash sub-device would create only V4L2_CID_FLASH_INDICATOR_INTENSITY control for it. There could ba also additional control added: V4L2_CID_FLASH_INDICATOR_PATTERN to support the feature supported by some LED class drivers. From the media device perspective such an approach would be harmful, as the indicator led could be turned on right I intended here wouldn't be harmful. before strobing the flash or turning the torch on, by separate calls to different v4l2-flash sub-devices. The design described above would allow for avoiding issues I touched in the message [1]. Regarding DT documentation: I would also swap the segments of a property name to follow the convention as in case of regulator-max-microamp. Updated version: == Optional properties for child nodes: - max-microamp : maximum intensity in microamperes of the LED (torch LED for flash devices) - flash-max-microamp : maximum intensity in microamperes of the flash LED; it is mandatory if the led should support the flash mode - flash-timeout-microsec : timeout in microseconds after which the flash led is turned off - indicator-pattern : identifier of the blinking pattern for the indicator led
Re: [RFC] adp1653: Add device tree bindings for LED controller
Hi Pavel, On 11/20/2014 01:12 PM, Pavel Machek wrote: Hi! I would also swap the segments of a property name to follow the convention as in case of regulator-max-microamp. Updated version: == Optional properties for child nodes: - max-microamp : maximum intensity in microamperes of the LED (torch LED for flash devices) - flash-max-microamp : maximum intensity in microamperes of the flash LED; it is mandatory if the led should support the flash mode - flash-timeout-microsec : timeout in microseconds after which the flash led is turned off Works for me. Do you want to submit a patch or should I do it? You can submit a patch for leds/common.txt and a separate patch for the adp1653 with a reference to the leds/common.txt for the child nodes. - indicator-pattern : identifier of the blinking pattern for the indicator led This would need a bit more documentation, no? - indicator-pattern : identifier of the blinking pattern for the indicator led; valid identifiers should be defined in the documentation of the parent node. I wouldn't go for pre-defined identifiers as the pattern can be a combination of various settings like ramp-up, ramp-down, pulse time etc. Drivers should expose only few combinations of these settings in my opinion, like e.g. leds-lm355x.c does. Regards, Jacek -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC] adp1653: Add device tree bindings for LED controller
Hi Pavel, Sakari, On 11/18/2014 05:51 PM, Pavel Machek wrote: Hi! If the hardware LED changes with one that needs different current, the block for the adp1653 stays the same, but white LED block should be updated with different value. I think that you are talking about sub nodes. Indeed I am leaning towards this type of design. I think I am :-). I agree that flash-timeout should be per led - an array, similarly as in case of iout's. Agreed about per-led, disagreed about the array. As all the fields would need arrays, and as LED system currently does not use arrays for label and linux,default-trigger, I believe we should follow existing design and model it as three devices. (It _is_ physically three devices.) Right, I missed that the leds/common.txt describes child node. I propose following modifications to the binding: Optional properties for child nodes: - iout-mode-led : maximum intensity in microamperes of the LED (torch LED for flash devices) - iout-mode-flash : initial intensity in microamperes of the flash LED; it is required to enable support for the flash led - iout-mode-indicator : initial intensity in microamperes of the indicator LED; it is required to enable support for the indicator led - max-iout-mode-led : maximum intensity in microamperes of the LED (torch LED for flash devices) - max-iout-mode-flash : maximum intensity in microamperes of the flash LED - max-iout-mode-indicator : maximum intensity in microamperes of the indicator LED - flash-timeout : timeout in microseconds after which flash led is turned off Ok, I took a look, and iout is notation I understand, but people may have trouble with and I don't see it used anywhere else. Also... do we need both current and max-current properties? But regulators already have regulator-max-microamp property. So what about: max-microamp : maximum intensity in microamperes of the LED (torch LED for flash devices) max-flash-microamp :initial intensity in microamperes of the flash LED; it is required to enable support for the flash led flash-timeout-microseconds : timeout in microseconds after which flash led is turned off If you had indicator on the same led, I guess indicator-microamp : recommended intensity in microamperes of the LED for indication ...would do? Ongoing discussion allowed me for taking a look at the indicator issue from different perspective. This is also vital for the issue of whether a v4l2-flash sub-device should be created per device or per sub-led [1]. Currently each sub-led is represented as a separate device tree sub node and the led drivers create separate LED class device for the sub nodes. What this implies is that indicator led also must be represented by the separate LED class device. This is contrary to the way how V4L2 Flash API approaches this issue, as it considers a flash device as a regulator chip driven through a bus. The API allows to set the led in torch or flash mode and implicitly assumes that there can be additional indicator led supported, which can't be turned on separately, but the drivers apply the indicator current to the indicator led when the torch or flash led is activated. I propose to create separate v4l2-flash device for the indicator led, and treat it as a regular sub-led similarly like it is done in the LED subsystem. LED Flash class driver would only add a flag LED_DEV_CAP_INDICATOR and basing on it the v4l2-flash sub-device would create only V4L2_CID_FLASH_INDICATOR_INTENSITY control for it. There could ba also additional control added: V4L2_CID_FLASH_INDICATOR_PATTERN to support the feature supported by some LED class drivers. From the media device perspective such an approach would be harmful, as the indicator led could be turned on right before strobing the flash or turning the torch on, by separate calls to different v4l2-flash sub-devices. The design described above would allow for avoiding issues I touched in the message [1]. Regarding DT documentation: I would also swap the segments of a property name to follow the convention as in case of regulator-max-microamp. Updated version: == Optional properties for child nodes: - max-microamp : maximum intensity in microamperes of the LED (torch LED for flash devices) - flash-max-microamp : maximum intensity in microamperes of the flash LED; it is mandatory if the led should support the flash mode - flash-timeout-microsec : timeout in microseconds after which the flash led is turned off - indicator-pattern :
Re: [RFC] adp1653: Add device tree bindings for LED controller
Hi Pavel, Sakari, On 11/17/2014 03:58 PM, Sakari Ailus wrote: Hi Pavel, On Sun, Nov 16, 2014 at 08:59:28AM +0100, Pavel Machek wrote: For device tree people: Yes, I know I'll have to create file in documentation, but does the binding below look acceptable? I'll clean up driver code a bit more, remove the printks. Anything else obviously wrong? Jacek Anaszewski is working on flash support for LED devices. I think it'd be good to sync the DT bindings for the two, as the types of devices supported by the LED API and the V4L2 flash API are quite similar. Cc Jacek. I've already submitted a patch [1] that updates leds common bindings. I hasn't been merged yet, as the related LED Flash class patch [2] still needs some indicator leds related discussion [3]. I think this is a good moment to discuss the flash related led common bindings. [1] http://www.spinics.net/lists/linux-leds/msg02121.html [2] http://www.spinics.net/lists/linux-media/msg83100.html [3] http://www.spinics.net/lists/linux-leds/msg02472.html Best Regards, Jacek Anaszewski -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC] adp1653: Add device tree bindings for LED controller
On 11/18/2014 09:46 AM, Pavel Machek wrote:
On Tue 2014-11-18 09:09:09, Jacek Anaszewski wrote:
Hi Pavel, Sakari,
On 11/17/2014 03:58 PM, Sakari Ailus wrote:
Hi Pavel,
On Sun, Nov 16, 2014 at 08:59:28AM +0100, Pavel Machek wrote:
For device tree people: Yes, I know I'll have to create file in
documentation, but does the binding below look acceptable?
I'll clean up driver code a bit more, remove the printks. Anything
else obviously wrong?
Jacek Anaszewski is working on flash support for LED devices. I think it'd
be good to sync the DT bindings for the two, as the types of devices
supported by the LED API and the V4L2 flash API are quite similar.
Cc Jacek.
I've already submitted a patch [1] that updates leds common bindings.
I hasn't been merged yet, as the related LED Flash class patch [2]
still needs some indicator leds related discussion [3].
I think this is a good moment to discuss the flash related led common
bindings.
Part of problem is that adp1653 is not regarded as LED device by
current kernel driver.
It doesn't prevent us from keeping the flash devices related
DT bindings unified across kernel subsystems. The DT bindings
docs for the adp1653 could just provide a reference to the
led/common.txt bindings. In the future, when LED Flash
class will be merged, all the V4L2 Flash drivers might be
moved to the LED subsystem to gain the LED subsystem support.
[1] http://www.spinics.net/lists/linux-leds/msg02121.html
@@ -3,6 +3,17 @@ Common leds properties.
Optional properties for child nodes:
- label : The label for this LED. If omitted, the label is
taken from the node name (excluding the unit address).
+- iout-torch : Array of maximum intensities in microamperes of the
torch
+ led currents in order from sub-led 0 to N-1, where N is the
number
+ of torch sub-leds exposed by the device
+- iout-flash : Array of maximum intensities in microamperes of the
flash
+ led currents in order from sub-led 0 to N-1, where N is the
number
+ of flash sub-leds exposed by the device
+- iout-indicator : Array of maximum intensities in microamperes of
+ the indicator led currents in order from sub-led 0 to N-1,
+ where N is the number of indicator sub-leds exposed by the device
+- flash-timeout : timeout in microseconds after which flash led
+ is turned off
- linux,default-trigger : This parameter, if present, is a
string defining the trigger assigned to the LED. Current
triggers are:
@@ -19,5 +30,10 @@ Examples:
system-status {
label = Status;
linux,default-trigger = heartbeat;
+ iout-torch = 500 500;
+ iout-flash = 1000 1000;
+ iout-indicator = 100 100;
+ flash-timeout = 1000;
+
...
};
I don't get it; system-status describes single LED, why are iout-torch
(and friends) arrays of two?
Some devices can control more than one led. The array is for such
purposes. The system-status should be probably renamed to
something more generic for both common leds and flash leds,
e.g. system-led.
Also, at least on adp1653, these are actually two leds -- white and
red. Torch and flash is white led, indicator is red led.
Then you should define three properties:
iout-torch = [uA];
iout-flash = [uA];
iout-indicator = [uA];
iout-torch and iout-flash properties would determine the current
for the white led in the torch and flash modes respectively and
the iout-indicator property would determine the current for
the indicator led.
[2] http://www.spinics.net/lists/linux-media/msg83100.html
[3] http://www.spinics.net/lists/linux-leds/msg02472.html
What device are you using for testing? Can you cc me on future
patches?
I am using max77693 [1] and aat1290 [2]. OK, I will add you on cc.
Why do we need complex flash LED class support, and where is the
V4L2 glue?
The rationale for unification of the LED and V4L2 Flash API
can be found in the discussion [3]. The glue is the v4l2-flash [4]
module which exposes a sub-device, that controls a LED Flash class
device with use of LED Flash class API.
The v4l2-flash sub-device registers with v4l2-async API
in a media device. Exemplary support for v4l2-flash
sub-devices is added to the exynos4-is driver in the patch [5].
Best Regards,
Jacek Anaszewski
[1] http://www.spinics.net/lists/linux-leds/msg02326.html
[2] http://www.spinics.net/lists/linux-media/msg81079.html
[3] http://www.spinics.net/lists/linux-media/msg69012.html
[4] http://www.spinics.net/lists/linux-leds/msg02322.html
[5] http://www.spinics.net/lists/linux-leds/msg02323.html
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Re: [RFC] adp1653: Add device tree bindings for LED controller
On 11/18/2014 12:32 PM, Pavel Machek wrote:
I've already submitted a patch [1] that updates leds common bindings.
I hasn't been merged yet, as the related LED Flash class patch [2]
still needs some indicator leds related discussion [3].
I think this is a good moment to discuss the flash related led common
bindings.
Part of problem is that adp1653 is not regarded as LED device by
current kernel driver.
It doesn't prevent us from keeping the flash devices related
DT bindings unified across kernel subsystems. The DT bindings
docs for the adp1653 could just provide a reference to the
led/common.txt bindings. In the future, when LED Flash
class will be merged, all the V4L2 Flash drivers might be
moved to the LED subsystem to gain the LED subsystem support.
Yeah, that makses sense.
@@ -19,5 +30,10 @@ Examples:
system-status {
label = Status;
linux,default-trigger = heartbeat;
+ iout-torch = 500 500;
+ iout-flash = 1000 1000;
+ iout-indicator = 100 100;
+ flash-timeout = 1000;
+
...
};
I don't get it; system-status describes single LED, why are iout-torch
(and friends) arrays of two?
Some devices can control more than one led. The array is for such
purposes. The system-status should be probably renamed to
something more generic for both common leds and flash leds,
e.g. system-led.
No, sorry. The Documentation/devicetree/bindings/leds/common.txt
describes binding for _one LED_. Yes, your device can have two leds,
so your devices should have two such blocks in the device tree... Each
led should have its own label and default trigger, for example. And I
guess flash-timeout be per-LED, too.
I think that a device tree binding describes a single physical device.
No matter how many sub-leds a device controls, it is still one
piece of hardware.
default-trigger property should also be an array of strings.
I agree that flash-timeout should be per led - an array, similarly
as in case of iout's.
Would it make sense to include -uA and -usec suffixes in the dt
property names?
I don't see this type of naming anywhere. The documentation should
contain the information about units. Nonetheless I am not a device tree
specialist, so an opinion of the relevant maintainer will be welcome.
Also, at least on adp1653, these are actually two leds -- white and
red. Torch and flash is white led, indicator is red led.
Then you should define three properties:
iout-torch = [uA];
iout-flash = [uA];
iout-indicator = [uA];
iout-torch and iout-flash properties would determine the current
for the white led in the torch and flash modes respectively and
the iout-indicator property would determine the current for
the indicator led.
Yes, that would work. I have used
+ max-flash-timeout-usec = 50;
+ max-flash-intensity-uA = 32;
+ max-torch-intensity-uA = 5;
+ max-indicator-intensity-uA = 17500;
. Which is pretty similar. (Actually, maybe the longer property names
are easier to understand for more people?) (And yes, I should probably
separate red and white led into separate groups).
Documentation of a binding should provide sufficient explanation
for the people to understand what a property is for.
And I would stay by arrays as argued above.
[2] http://www.spinics.net/lists/linux-media/msg83100.html
[3] http://www.spinics.net/lists/linux-leds/msg02472.html
What device are you using for testing? Can you cc me on future
patches?
I am using max77693 [1] and aat1290 [2]. OK, I will add you on cc.
Thanks for cc and thanks for links!
I see max77693 has two different white leds, aat1290 has one white
led, and neither of them has secondary red led for indication?
You're right.
The v4l2-flash sub-device registers with v4l2-async API
in a media device. Exemplary support for v4l2-flash
sub-devices is added to the exynos4-is driver in the patch [5].
Thanks for the links. It seems that aside from moving adp1653 driver
to device tree, it should be moved to the LED framework, but that's a
topic for another patch.
Like I mentioned in the previous message the LED Flash class patch
isn't in its final shape yet. Nonetheless I think that we should
agree on the leds/common.txt documentation improvements and
define DT documentation for adp1653 accordingly.
Regards,
Jacek
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Re: [RFC] adp1653: Add device tree bindings for LED controller
Hi Pavel,
On 11/18/2014 02:21 PM, Pavel Machek wrote:
Hi!
@@ -19,5 +30,10 @@ Examples:
system-status {
label = Status;
linux,default-trigger = heartbeat;
+ iout-torch = 500 500;
+ iout-flash = 1000 1000;
+ iout-indicator = 100 100;
+ flash-timeout = 1000;
+
...
};
I don't get it; system-status describes single LED, why are iout-torch
(and friends) arrays of two?
Some devices can control more than one led. The array is for such
purposes. The system-status should be probably renamed to
something more generic for both common leds and flash leds,
e.g. system-led.
No, sorry. The Documentation/devicetree/bindings/leds/common.txt
describes binding for _one LED_. Yes, your device can have two leds,
so your devices should have two such blocks in the device tree... Each
led should have its own label and default trigger, for example. And I
guess flash-timeout be per-LED, too.
I think that a device tree binding describes a single physical device.
No matter how many sub-leds a device controls, it is still one
piece of hardware.
You got this wrong, sorry.
In my case, there are three physical devices:
adp1653
white LED
red LED
You've mentioned that your white led is torch/flash and indicator
is the red led. They are probably connected to the HPLED and
ILED pins of the ADP1653 device respectively. The device is just
a regulator, that delivers electric current to the leds connected
to it. Kernel cannot directly activate leds, but has to talk
to the device through I2C bus. One I2C device can have only one
related device tree binding.
Each LED should have an label, and probably default trigger -- default
trigger for red one should be we are recording video and for white
should be this is flash for default camera.
default-trigger is not mandatory, the device doesn't have to have
associated led-trigger. I think that you should look at
Documentation/leds/leds-class.txt and drivers/leds/triggers for
more detailed information. In a nutshell triggers are kernel
sources of led events. You can set e.g. heartbeat, timer
trigger etc.
As for now the driver belongs to the V4L2 subsystem it doesn't
support triggers. Moreover your event we are recording a video
should be activated by setting V4L2_CID_FLASH_INDICATOR_INTENSITY
v4l2 control followed by V4L2_FLASH_LED_MODE_TORCH. Your event
this is flash for default camera seems to be flash strobe,
that can be activated by setting V4L2_CID_FLASH_STROBE control.
The driver by default sets the indicator current for both actions
to the value previously set with V4L2_CID_FLASH_INDICATOR_INTENSITY.
If the hardware LED changes with one that needs different current, the
block for the adp1653 stays the same, but white LED block should be
updated with different value.
I think that you are talking about sub nodes. Indeed I am leaning
towards this type of design.
default-trigger property should also be an array of strings.
That is not how it currently works.
OK, I agree.
I agree that flash-timeout should be per led - an array, similarly
as in case of iout's.
Agreed about per-led, disagreed about the array. As all the fields
would need arrays, and as LED system currently does not use arrays for
label and linux,default-trigger, I believe we should follow existing
design and model it as three devices. (It _is_ physically three devices.)
Right, I missed that the leds/common.txt describes child node.
I propose following modifications to the binding:
Optional properties for child nodes:
- iout-mode-led : maximum intensity in microamperes of the LED
(torch LED for flash devices)
- iout-mode-flash : initial intensity in microamperes of the
flash LED; it is required to enable support
for the flash led
- iout-mode-indicator : initial intensity in microamperes of the
indicator LED; it is required to enable support
for the indicator led
- max-iout-mode-led : maximum intensity in microamperes of the LED
(torch LED for flash devices)
- max-iout-mode-flash : maximum intensity in microamperes of the
flash LED
- max-iout-mode-indicator : maximum intensity in microamperes of the
indicator LED
- flash-timeout : timeout in microseconds after which flash
led is turned off
system-status {
label = max77693_1;
iout-mode-led = 500;
max-iout-mode-led = 500;
...
};
camera-flash1 {
label = max77693_2;
iout-mode-led = 500;
iout-mode-flash = 1000;
iout-mode-indicator = 100;
max-iout-mode-led = 500;
max-iout-mode-flash = 1000;
max-iout-mode-indicator = 100;
flash-timeout = 1000;
...
};
I propose to avoid name torch, as for ordinary leds it would
