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| author | Xu Yang <xu.yang_2@nxp.com> | 2026-01-13 17:53:08 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-01-23 11:21:27 +0100 |
| commit | aee473246134b33dbb5e2b58926b59632a84a223 (patch) | |
| tree | 14a5e94442b5623206ead390486b94beae55d8df | |
| parent | 34f6634dba87ef72b3c3a3a524be663adef7ab42 (diff) | |
| download | linux-aee473246134b33dbb5e2b58926b59632a84a223.tar.gz linux-aee473246134b33dbb5e2b58926b59632a84a223.tar.bz2 linux-aee473246134b33dbb5e2b58926b59632a84a223.zip | |
usb: gadget: uvc: fix interval_duration calculation
commit 010dc57cb5163e5f4a32430dd5091cc29efd0471 upstream.
According to USB specification:
For full-/high-speed isochronous endpoints, the bInterval value is
used as the exponent for a 2^(bInterval-1) value.
To correctly convert bInterval as interval_duration:
interval_duration = 2^(bInterval-1) * frame_interval
Because the unit of video->interval is 100ns, add a comment info to
make it clear.
Fixes: 48dbe731171e ("usb: gadget: uvc: set req_size and n_requests based on the frame interval")
Cc: stable@vger.kernel.org
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Link: https://patch.msgid.link/20260113-uvc-gadget-fix-patch-v2-2-62950ef5bcb5@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/gadget/function/uvc.h | 2 | ||||
| -rw-r--r-- | drivers/usb/gadget/function/uvc_video.c | 7 |
2 files changed, 6 insertions, 3 deletions
diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h index 9e79cbe50715..791a3b956cf2 100644 --- a/drivers/usb/gadget/function/uvc.h +++ b/drivers/usb/gadget/function/uvc.h @@ -107,7 +107,7 @@ struct uvc_video { unsigned int width; unsigned int height; unsigned int imagesize; - unsigned int interval; + unsigned int interval; /* in 100ns units */ struct mutex mutex; /* protects frame parameters */ unsigned int uvc_num_requests; diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c index fb77b0b21790..7f5690713bc0 100644 --- a/drivers/usb/gadget/function/uvc_video.c +++ b/drivers/usb/gadget/function/uvc_video.c @@ -499,7 +499,7 @@ uvc_video_prep_requests(struct uvc_video *video) { struct uvc_device *uvc = container_of(video, struct uvc_device, video); struct usb_composite_dev *cdev = uvc->func.config->cdev; - unsigned int interval_duration = video->ep->desc->bInterval * 1250; + unsigned int interval_duration; unsigned int max_req_size, req_size, header_size; unsigned int nreq; @@ -515,8 +515,11 @@ uvc_video_prep_requests(struct uvc_video *video) return; } + interval_duration = 2 << (video->ep->desc->bInterval - 1); if (cdev->gadget->speed < USB_SPEED_HIGH) - interval_duration = video->ep->desc->bInterval * 10000; + interval_duration *= 10000; + else + interval_duration *= 1250; nreq = DIV_ROUND_UP(video->interval, interval_duration); |