[PATCH AUTOSEL 4.9 02/12] usb: gadget: uvc: add bInterval checking for HS mode

[Sasha Levin]

From: Pawel Laszczak <pawell@xxxxxxxxxxx>

[ Upstream commit 26adde04acdff14a1f28d4a5dce46a8513a3038b ]

Patch adds extra checking for bInterval passed by configfs.
The 5.6.4 chapter of USB Specification (rev. 2.0) say:
"A high-bandwidth endpoint must specify a period of 1x125 µs
(i.e., a bInterval value of 1)."

The issue was observed during testing UVC class on CV.
I treat this change as improvement because we can control
bInterval by configfs.

Reviewed-by: Peter Chen <peter.chen@xxxxxxxxxx>
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210308125338.4824-1-pawell@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/usb/gadget/function/f_uvc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index f8a1881609a2..89da34ef7b3f 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -625,7 +625,12 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 
 	uvc_hs_streaming_ep.wMaxPacketSize =
 		cpu_to_le16(max_packet_size | ((max_packet_mult - 1) << 11));
-	uvc_hs_streaming_ep.bInterval = opts->streaming_interval;
+
+	/* A high-bandwidth endpoint must specify a bInterval value of 1 */
+	if (max_packet_mult > 1)
+		uvc_hs_streaming_ep.bInterval = 1;
+	else
+		uvc_hs_streaming_ep.bInterval = opts->streaming_interval;
 
 	uvc_ss_streaming_ep.wMaxPacketSize = cpu_to_le16(max_packet_size);
 	uvc_ss_streaming_ep.bInterval = opts->streaming_interval;
-- 
2.30.2