[PATCH v2] usb: dwc3: gadget: Remove FS bInterval_m1 limitation

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

The programming guide incorrectly stated that the DCFG.bInterval_m1 must
be set to 0 when operating in fullspeed. There's no such limitation for
all IPs. See DWC_usb3x programming guide section 3.2.2.1.

Cc: <stable@vger.kernel.org>
Fixes: a1679af85b2a ("usb: dwc3: gadget: Fix setting of DEPCFG.bInterval_m1")
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
 Changes in v2:
 - Noted programming guide section number

 drivers/usb/dwc3/gadget.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 6227641f2d31..3609311b24f1 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -608,12 +608,14 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
 		u8 bInterval_m1;
 
 		/*
-		 * Valid range for DEPCFG.bInterval_m1 is from 0 to 13, and it
-		 * must be set to 0 when the controller operates in full-speed.
+		 * Valid range for DEPCFG.bInterval_m1 is from 0 to 13.
+		 *
+		 * NOTE: The programming guide incorrectly stated bInterval_m1
+		 * must be set to 0 when operating in fullspeed. Internally the
+		 * controller does not have this limitation. See DWC_usb3x
+		 * programming guide section 3.2.2.1.
 		 */
 		bInterval_m1 = min_t(u8, desc->bInterval - 1, 13);
-		if (dwc->gadget->speed == USB_SPEED_FULL)
-			bInterval_m1 = 0;
 
 		if (usb_endpoint_type(desc) == USB_ENDPOINT_XFER_INT &&
 		    dwc->gadget->speed == USB_SPEED_FULL)

base-commit: 4b853c236c7b5161a2e444bd8b3c76fe5aa5ddcb
-- 
2.28.0