[PATCH v8] media: uvcvideo: Fix bandwidth issue for Alcor camera.

[PATCH v8] media: uvcvideo: Fix bandwidth issue for Alcor camera.

[chenchangcheng]

From: chenchangcheng <chenchangcheng@kylinos.cn>

Some broken device return wrong dwMaxPayloadTransferSize fields
as follows:
    [  218.632537] [pid:20427,cpu6,guvcview,8]uvcvideo: Device requested 2752512 B/frame bandwidth.
    [  218.632598] [pid:20427,cpu6,guvcview,9]uvcvideo: No fast enough alt setting for requested bandwidth.

When dwMaxPayloadTransferSize is greater than maxpsize,
it will prevent the camera from starting.
So use the bandwidth of maxpsize.

Signed-off-by: chenchangcheng <chenchangcheng@kylinos.cn>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202505072016.LlOxF8BG-lkp@intel.com/
---
 drivers/media/usb/uvc/uvc_video.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index e3567aeb0007..0d5c17509ceb 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -262,6 +262,15 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
 
 		ctrl->dwMaxPayloadTransferSize = bandwidth;
 	}
+
+	if (stream->intf->num_altsetting > 1 &&
+	    ctrl->dwMaxPayloadTransferSize > stream->maxpsize) {
+		dev_warn_ratelimited(&stream->intf->dev,
+				   "the max payload transmission size (%d) exceededs the size of the ep max packet (%d). Using the max size.\n",
+				   ctrl->dwMaxPayloadTransferSize,
+				   stream->maxpsize);
+		ctrl->dwMaxPayloadTransferSize = stream->maxpsize;
+	}
 }
 
 static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)

base-commit: d76bb1ebb5587f66b0f8b8099bfbb44722bc08b3
-- 
2.25.1

[PATCH v8] media: uvcvideo: Fix bandwidth issue for Alcor camera.

[chenchangcheng]

From: chenchangcheng <chenchangcheng@kylinos.cn>

Some broken device return wrong dwMaxPayloadTransferSize fields
as follows:
    [  218.632537] [pid:20427,cpu6,guvcview,8]uvcvideo: Device requested 2752512 B/frame bandwidth.
    [  218.632598] [pid:20427,cpu6,guvcview,9]uvcvideo: No fast enough alt setting for requested bandwidth.

When dwMaxPayloadTransferSize is greater than maxpsize,
it will prevent the camera from starting.
So use the bandwidth of maxpsize.

Signed-off-by: chenchangcheng <chenchangcheng@kylinos.cn>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202505072016.LlOxF8BG-lkp@intel.com/
---
 drivers/media/usb/uvc/uvc_video.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index e3567aeb0007..0d5c17509ceb 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -262,6 +262,15 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
 
 		ctrl->dwMaxPayloadTransferSize = bandwidth;
 	}
+
+	if (stream->intf->num_altsetting > 1 &&
+	    ctrl->dwMaxPayloadTransferSize > stream->maxpsize) {
+		dev_warn_ratelimited(&stream->intf->dev,
+				   "the max payload transmission size (%d) exceededs the size of the ep max packet (%d). Using the max size.\n",
+				   ctrl->dwMaxPayloadTransferSize,
+				   stream->maxpsize);
+		ctrl->dwMaxPayloadTransferSize = stream->maxpsize;
+	}
 }
 
 static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)

base-commit: b4432656b36e5cc1d50a1f2dc15357543add530e
-- 
2.25.1

Re: [PATCH v8] media: uvcvideo: Fix bandwidth issue for Alcor camera.

[Ricardo Ribalda]

Hi

Could you please resend ccing linux-media? Otherwise the patch wont be
processed.

Regards!


On Thu, 8 May 2025 at 03:56, chenchangcheng <ccc194101@163.com> wrote:
>
> From: chenchangcheng <chenchangcheng@kylinos.cn>
>
> Some broken device return wrong dwMaxPayloadTransferSize fields
> as follows:
>     [  218.632537] [pid:20427,cpu6,guvcview,8]uvcvideo: Device requested 2752512 B/frame bandwidth.
>     [  218.632598] [pid:20427,cpu6,guvcview,9]uvcvideo: No fast enough alt setting for requested bandwidth.
>
> When dwMaxPayloadTransferSize is greater than maxpsize,
> it will prevent the camera from starting.
> So use the bandwidth of maxpsize.
>
> Signed-off-by: chenchangcheng <chenchangcheng@kylinos.cn>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202505072016.LlOxF8BG-lkp@intel.com/
There is no need to add the reported-by and closes:
The patch has not landed any tree yet.

> ---
>  drivers/media/usb/uvc/uvc_video.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
> index e3567aeb0007..0d5c17509ceb 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -262,6 +262,15 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
>
>                 ctrl->dwMaxPayloadTransferSize = bandwidth;
>         }
> +
> +       if (stream->intf->num_altsetting > 1 &&
> +           ctrl->dwMaxPayloadTransferSize > stream->maxpsize) {
> +               dev_warn_ratelimited(&stream->intf->dev,
> +                                  "the max payload transmission size (%d) exceededs the size of the ep max packet (%d). Using the max size.\n",
> +                                  ctrl->dwMaxPayloadTransferSize,
> +                                  stream->maxpsize);
> +               ctrl->dwMaxPayloadTransferSize = stream->maxpsize;
> +       }
>  }
>
>  static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)
>
> base-commit: b4432656b36e5cc1d50a1f2dc15357543add530e
> --
> 2.25.1
>


--
Ricardo Ribalda