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 --- Changes in v2: - replace int_pow with left shift - add R-b tag --- drivers/usb/gadget/function/uvc.h | 2 +- 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 b3f88670bff801a43d084646974602e5995bb192..676419a049762f9eb59e1ac68b19fa34f153b793 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 1c0672f707e4e5f29c937a1868f0400aad62e5cb..9dc3af16e2f38957198bf579987f4324fc552c5d 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);