From: Xu Yang Date: Tue, 13 Jan 2026 09:53:08 +0000 (+0800) Subject: usb: gadget: uvc: fix interval_duration calculation X-Git-Tag: v6.19-rc6~7^2~4 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=010dc57cb5163e5f4a32430dd5091cc29efd0471;p=thirdparty%2Flinux.git usb: gadget: uvc: fix interval_duration calculation 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 Signed-off-by: Xu Yang Link: https://patch.msgid.link/20260113-uvc-gadget-fix-patch-v2-2-62950ef5bcb5@nxp.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h index b3f88670bff8..676419a04976 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 1c0672f707e4..9dc3af16e2f3 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; @@ -513,8 +513,11 @@ 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);