Am 18.10.2013 22:30, schrieb Guennadi Liakhovetski:
> Hi Frank
>
> Thanks for the patch
>
> On Wed, 16 Oct 2013, Frank Schäfer wrote:
>
>> Commit 622b828ab7 ("v4l2_subdev: rename tuner s_standby operation to
>> core s_power") replaced the tuner s_standby call in the em28xx driver with
>> a (s_power, 0) call which suspends all subdevices.
>> But it neglected to add corresponding (s_power, 1) calls to make sure that
>> the subdevices are powered on again when needed.
>>
>> This patch fixes this issue by adding a (s_power, 1) call to
>> function em28xx_wake_i2c().
>>
>> Signed-off-by: Frank Schäfer <[email protected]>
>> ---
>> drivers/media/usb/em28xx/em28xx-core.c | 1 +
>> 1 Datei geändert, 1 Zeile hinzugefügt(+)
>>
>> diff --git a/drivers/media/usb/em28xx/em28xx-core.c
>> b/drivers/media/usb/em28xx/em28xx-core.c
>> index fc157af..8896789 100644
>> --- a/drivers/media/usb/em28xx/em28xx-core.c
>> +++ b/drivers/media/usb/em28xx/em28xx-core.c
>> @@ -1243,6 +1243,7 @@ EXPORT_SYMBOL_GPL(em28xx_init_usb_xfer);
>> */
>> void em28xx_wake_i2c(struct em28xx *dev)
>> {
>> + v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_power, 1);
>> v4l2_device_call_all(&dev->v4l2_dev, 0, core, reset, 0);
>> v4l2_device_call_all(&dev->v4l2_dev, 0, video, s_routing,
>> INPUT(dev->ctl_input)->vmux, 0, 0);
> Do I understand it right, that you're proposing this as an alternative to
> my power-balancing patch?
Yes.
Your patch was nevertheless useful, because it pointed out further bugs
in em28xx_v4l2_open().
I've sent another RFC patch which should fix them, too.
> It's certainly smaller and simpler, have you
> also tested it with the ov2640 and my clock patches to see, whether this
> really balances calls to .s_power() perfectly?
Yes, I've tested the patch with the VAD Laplace webcam (ov2640), a
Hauppauge HVR 900 and a Terratec Cinergy 200.
Please note that the patch does not balance .s_power() calls perfectly,
it only makes sure that the subdevices are powered on when needed.
This also avoids the scary v4l2-clk warnings.
Due to the various GPIO sequences, I see no chance to make s_power calls
really balanced in such drivers.
Regards,
Frank
> Thanks
> Guennadi
> ---
> Guennadi Liakhovetski, Ph.D.
> Freelance Open-Source Software Developer
> http://www.open-technology.de/
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