linux-kernel - Re: [PATCH] media: uvcvideo: Fix power line control for a Chicony camera

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Date:   Fri, 18 Aug 2023 11:16:42 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Ricardo Ribalda <ribalda@...omium.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: uvcvideo: Fix power line control for a Chicony
 camera

On Fri, Aug 18, 2023 at 11:15:47AM +0300, Laurent Pinchart wrote:
> Hi Ricardo,
> 
> Thank you for the patch.
> 
> On Thu, Aug 17, 2023 at 12:38:04PM +0000, Ricardo Ribalda wrote:
> > The device does not implement the control properly.
> > 
> > Fixes vl2-compliance error:

I will also s/vl2/v4l2/ locally :-)

> > 
> > info: checking control 'Power Line Frequency' (0x00980918)
> > fail: v4l2-test-controls.cpp(552): could not set valid menu item 3
> > 
> > Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> > ---
> > This camera, like other Chicony devices, do not implement properly the
> > Power Line Frequency control.
> > 
> > This time, I do not have direct access to the device, just to the
> > report, but since other devices from the same family are showing the
> > same error, it is safe to assume that the same fix will work here.
> 
> Why, ô why does UVC not provide a way to query this dynamically ? :-( Of
> course, even if it did, I'm sure vendors would get it wrong... It sounds
> like the Windows UVC compliance test suite must be a joke.
> 
> > ---
> >  drivers/media/usb/uvc/uvc_driver.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > index 08fcd2ffa727..db2556e95b72 100644
> > --- a/drivers/media/usb/uvc/uvc_driver.c
> > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > @@ -2592,6 +2592,15 @@ static const struct usb_device_id uvc_ids[] = {
> >  	  .bInterfaceSubClass	= 1,
> >  	  .bInterfaceProtocol	= 0,
> >  	  .driver_info		= (kernel_ulong_t)&uvc_ctrl_power_line_limited },
> > +	/* Chicony Electronics Co., Ltd */
> 
> I'll write
> 
> 	/* Chicony Electronics Co., Ltd Integrated Camera */
> 
> as that's what the descriptors expose. Is this integrated in a
> chromebook by any chance ? If so, could you share which model the camera
> is found in, and can I add that to the comment ?
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> 
> > +	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
> > +				| USB_DEVICE_ID_MATCH_INT_INFO,
> > +	  .idVendor		= 0x04f2,
> > +	  .idProduct		= 0xb67c,
> > +	  .bInterfaceClass	= USB_CLASS_VIDEO,
> > +	  .bInterfaceSubClass	= 1,
> > +	  .bInterfaceProtocol	= 0,
> > +	  .driver_info		= (kernel_ulong_t)&uvc_ctrl_power_line_limited },
> >  	/* Chicony EasyCamera */
> >  	{ .match_flags		= USB_DEVICE_ID_MATCH_DEVICE
> >  				| USB_DEVICE_ID_MATCH_INT_INFO,
> > 
> > ---
> > base-commit: 4853c74bd7ab7fdb83f319bd9ace8a08c031e9b6
> > change-id: 20230817-chicony-9c35f2046c6f

-- 
Regards,

Laurent Pinchart