[PATCH v4] media: uvcvideo: Fix bandwidth error for Alcor camera

From: Ai Chao
Date: Tue Nov 22 2022 - 03:49:50 EST


For Alcor Corp. Slave camera(1b17:6684/2017:0011), it support to output
compressed video data, and it return a wrong dwMaxPayloadTransferSize
fields. This is a fireware issue, but the manufacturer cannot provide
a const return fieldsby the fireware. For some device, it requested
2752512 B/frame bandwidth. For normally device, it requested 3072 or 1024
B/frame bandwidth. so we check the dwMaxPayloadTransferSize fields,if it
large than 0x1000, reset dwMaxPayloadTransferSize to 1024, and the camera
preview normally.

Signed-off-by: Ai Chao <aichao@xxxxxxxxxx>

---
change for v4
- Change usb_match_one_id to usb_match_id
- Modify the discription

change for v3
- Add VID/PID 2017:0011

change for v2
- Used usb_match_one_id to check VID and PID
---
---
drivers/media/usb/uvc/uvc_video.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index d2eb9066e4dc..75bdd71d0e5a 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -135,6 +135,11 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
static const struct usb_device_id elgato_cam_link_4k = {
USB_DEVICE(0x0fd9, 0x0066)
};
+ static const struct usb_device_id alcor_corp_slave_cam[] = {
+ { USB_DEVICE(0x2017, 0x0011) },
+ { USB_DEVICE(0x1b17, 0x6684) },
+ { }
+ };
struct uvc_format *format = NULL;
struct uvc_frame *frame = NULL;
unsigned int i;
@@ -234,6 +239,13 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,

ctrl->dwMaxPayloadTransferSize = bandwidth;
}
+
+ /* Alcor Corp. Slave camera return wrong dwMaxPayloadTransferSize */
+ if ((format->flags & UVC_FMT_FLAG_COMPRESSED) &&
+ (ctrl->dwMaxPayloadTransferSize > 0x1000) &&
+ usb_match_id(stream->dev->intf, alcor_corp_slave_cam)) {
+ ctrl->dwMaxPayloadTransferSize = 1024;
+ }
}

static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)
--
2.25.1