Date:   Thu, 9 Mar 2023 14:30:30 +0900
From:   Sergey Senozhatsky <senozhatsky@chromium.org>
To:     Ricardo Ribalda <ribalda@chromium.org>
Cc:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        "hn.chen" <hn.chen@sunplusit.com>, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org
Subject: Re: [PATCH RESEND v5 2/5] media: uvcvideo: Quirk for invalid dev_sof
 in Logitech C922
Message-ID: <20230309053030.GB1045797@google.com>
References: <20220920-resend-hwtimestamp-v5-0-139d1a144614@chromium.org>
 <20220920-resend-hwtimestamp-v5-2-139d1a144614@chromium.org>
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On (23/03/08 23:45), Ricardo Ribalda wrote:
[..]
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -541,7 +541,13 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
>  
>  	stream->clock.last_sof = dev_sof;
>  
> -	host_sof = usb_get_current_frame_number(stream->dev->udev);

What host_sof is set to? Some stack garbage?

> +	/*
> +	 * On some devices, like the Logitech C922, the device SOF does not run
> +	 * at a stable rate of 1kHz. For those devices use the host SOF instead.
> +	 */
> +	if (stream->dev->quirks & UVC_QUIRK_INVALID_DEVICE_SOF)
> +		dev_sof = usb_get_current_frame_number(stream->dev->udev);
> +
>  	time = uvc_video_get_time();