[PATCH 1/2] usb: dwc3: gadget: Fix setting of DEPCFG.bInterval_m1

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

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. See the programming
guide for DEPCFG command section 3.2.2.1 (v3.30a).

Cc: <stable@vger.kernel.org>
Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
 drivers/usb/dwc3/gadget.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 97d707b4f384..d0f8d3ec855f 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -605,7 +605,17 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
 		params.param0 |= DWC3_DEPCFG_FIFO_NUMBER(dep->number >> 1);
 
 	if (desc->bInterval) {
-		params.param1 |= DWC3_DEPCFG_BINTERVAL_M1(desc->bInterval - 1);
+		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.
+		 */
+		bInterval_m1 = min_t(u8, desc->bInterval - 1, 13);
+		if (dwc->gadget->speed == USB_SPEED_FULL)
+			bInterval_m1 = 0;
+
+		params.param1 |= DWC3_DEPCFG_BINTERVAL_M1(bInterval_m1);
 		dep->interval = 1 << (desc->bInterval - 1);
 	}
 
-- 
2.28.0