drivers/media/usb/uvc/uvc_video.c | 9 +++++++++ 1 file changed, 9 insertions(+)
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>
---
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..9b7e34e38b61 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_ratelimit(&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: 8ffd015db85fea3e15a77027fda6c02ced4d2444
--
2.25.1Hi chenchangcheng,
kernel test robot noticed the following build errors:
[auto build test ERROR on 8ffd015db85fea3e15a77027fda6c02ced4d2444]
url: https://github.com/intel-lab-lkp/linux/commits/chenchangcheng/media-uvcvideo-Fix-bandwidth-issue/20250416-140638
base: 8ffd015db85fea3e15a77027fda6c02ced4d2444
patch link: https://lore.kernel.org/r/20250416031838.254061-1-ccc194101%40163.com
patch subject: [PATCH v7] media: uvcvideo: Fix bandwidth issue
config: i386-randconfig-012-20250424 (https://download.01.org/0day-ci/archive/20250507/202505072016.LlOxF8BG-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250507/202505072016.LlOxF8BG-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505072016.LlOxF8BG-lkp@intel.com/
All errors (new ones prefixed by >>):
drivers/media/usb/uvc/uvc_video.c: In function 'uvc_fixup_video_ctrl':
>> drivers/media/usb/uvc/uvc_video.c:268:17: error: implicit declaration of function 'dev_warn_ratelimit'; did you mean 'dev_warn_ratelimited'? [-Werror=implicit-function-declaration]
268 | dev_warn_ratelimit(&stream->intf->dev,
| ^~~~~~~~~~~~~~~~~~
| dev_warn_ratelimited
cc1: some warnings being treated as errors
vim +268 drivers/media/usb/uvc/uvc_video.c
162
163 static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
164 struct uvc_streaming_control *ctrl)
165 {
166 const struct uvc_format *format = NULL;
167 const struct uvc_frame *frame = NULL;
168 unsigned int i;
169
170 /*
171 * The response of the Elgato Cam Link 4K is incorrect: The second byte
172 * contains bFormatIndex (instead of being the second byte of bmHint).
173 * The first byte is always zero. The third byte is always 1.
174 *
175 * The UVC 1.5 class specification defines the first five bits in the
176 * bmHint bitfield. The remaining bits are reserved and should be zero.
177 * Therefore a valid bmHint will be less than 32.
178 *
179 * Latest Elgato Cam Link 4K firmware as of 2021-03-23 needs this fix.
180 * MCU: 20.02.19, FPGA: 67
181 */
182 if (usb_match_one_id(stream->dev->intf, &elgato_cam_link_4k) &&
183 ctrl->bmHint > 255) {
184 u8 corrected_format_index = ctrl->bmHint >> 8;
185
186 uvc_dbg(stream->dev, VIDEO,
187 "Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: %u} to {bmHint: 0x%04x, bFormatIndex: %u}\n",
188 ctrl->bmHint, ctrl->bFormatIndex,
189 1, corrected_format_index);
190 ctrl->bmHint = 1;
191 ctrl->bFormatIndex = corrected_format_index;
192 }
193
194 for (i = 0; i < stream->nformats; ++i) {
195 if (stream->formats[i].index == ctrl->bFormatIndex) {
196 format = &stream->formats[i];
197 break;
198 }
199 }
200
201 if (format == NULL)
202 return;
203
204 for (i = 0; i < format->nframes; ++i) {
205 if (format->frames[i].bFrameIndex == ctrl->bFrameIndex) {
206 frame = &format->frames[i];
207 break;
208 }
209 }
210
211 if (frame == NULL)
212 return;
213
214 if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) ||
215 (ctrl->dwMaxVideoFrameSize == 0 &&
216 stream->dev->uvc_version < 0x0110))
217 ctrl->dwMaxVideoFrameSize =
218 frame->dwMaxVideoFrameBufferSize;
219
220 /*
221 * The "TOSHIBA Web Camera - 5M" Chicony device (04f2:b50b) seems to
222 * compute the bandwidth on 16 bits and erroneously sign-extend it to
223 * 32 bits, resulting in a huge bandwidth value. Detect and fix that
224 * condition by setting the 16 MSBs to 0 when they're all equal to 1.
225 */
226 if ((ctrl->dwMaxPayloadTransferSize & 0xffff0000) == 0xffff0000)
227 ctrl->dwMaxPayloadTransferSize &= ~0xffff0000;
228
229 if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) &&
230 stream->dev->quirks & UVC_QUIRK_FIX_BANDWIDTH &&
231 stream->intf->num_altsetting > 1) {
232 u32 interval;
233 u32 bandwidth;
234
235 interval = (ctrl->dwFrameInterval > 100000)
236 ? ctrl->dwFrameInterval
237 : frame->dwFrameInterval[0];
238
239 /*
240 * Compute a bandwidth estimation by multiplying the frame
241 * size by the number of video frames per second, divide the
242 * result by the number of USB frames (or micro-frames for
243 * high- and super-speed devices) per second and add the UVC
244 * header size (assumed to be 12 bytes long).
245 */
246 bandwidth = frame->wWidth * frame->wHeight / 8 * format->bpp;
247 bandwidth *= 10000000 / interval + 1;
248 bandwidth /= 1000;
249 if (stream->dev->udev->speed >= USB_SPEED_HIGH)
250 bandwidth /= 8;
251 bandwidth += 12;
252
253 /*
254 * The bandwidth estimate is too low for many cameras. Don't use
255 * maximum packet sizes lower than 1024 bytes to try and work
256 * around the problem. According to measurements done on two
257 * different camera models, the value is high enough to get most
258 * resolutions working while not preventing two simultaneous
259 * VGA streams at 15 fps.
260 */
261 bandwidth = max_t(u32, bandwidth, 1024);
262
263 ctrl->dwMaxPayloadTransferSize = bandwidth;
264 }
265
266 if (stream->intf->num_altsetting > 1 &&
267 ctrl->dwMaxPayloadTransferSize > stream->maxpsize) {
> 268 dev_warn_ratelimit(&stream->intf->dev,
269 "the max payload transmission size (%d) exceededs the size of the ep max packet (%d). Using the max size.\n",
270 ctrl->dwMaxPayloadTransferSize,
271 stream->maxpsize);
272 ctrl->dwMaxPayloadTransferSize = stream->maxpsize;
273 }
274 }
275
--
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