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

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Date:   Fri, 18 Aug 2023 11:15:46 +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

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:
> 
> 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