usb: dwc3: gadget: update DCFG.NumP to max burst size

NumP field of DCFG register is used on NumP field of
ACK TP header and it tells the host how many packets
an endpoint can receive before waiting for
synchronization.

Documentation says it should be set to anything
<=bMaxBurst. Interestingly, however, this setting is
not per-endpoint how it should be (different
endpoints could have different burst sizes), but
things seem to work okay right now.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/core.h

@@ -271,6 +271,9 @@
 #define DWC3_DCFG_LOWSPEED	(2 << 0)
 #define DWC3_DCFG_FULLSPEED1	(3 << 0)
 
+#define DWC3_DCFG_NUMP_SHIFT	17
+#define DWC3_DCFG_NUMP(n)	(((n) & 0x1f) >> DWC3_DCFG_NUMP_SHIFT)
+#define DWC3_DCFG_NUMP_MASK	(0x1f << DWC3_DCFG_NUMP_SHIFT)
 #define DWC3_DCFG_LPM_CAP	(1 << 22)
 
 /* Device Control Register */

drivers/usb/dwc3/gadget.c

@@ -464,9 +464,19 @@ static int dwc3_gadget_set_ep_config(struct dwc3 *dwc, struct dwc3_ep *dep,
 
 	/* Burst size is only needed in SuperSpeed mode */
 	if (dwc->gadget.speed >= USB_SPEED_SUPER) {
-		u32 burst = dep->endpoint.maxburst - 1;
+		u32 burst = dep->endpoint.maxburst;
+		u32 nump;
+		u32 reg;
 
-		params.param0 |= DWC3_DEPCFG_BURST_SIZE(burst);
+		/* update NumP */
+		reg = dwc3_readl(dwc->regs, DWC3_DCFG);
+		nump = DWC3_DCFG_NUMP(reg);
+		nump = max(nump, burst);
+		reg &= ~DWC3_DCFG_NUMP_MASK;
+		reg |= nump << DWC3_DCFG_NUMP_SHIFT;
+		dwc3_writel(dwc->regs, DWC3_DCFG, reg);
+
+		params.param0 |= DWC3_DEPCFG_BURST_SIZE(burst - 1);
 	}
 
 	if (ignore)