usb: dwc2: fix bulk transfers

When I created wait_for_chhltd(), I noticed that some instances of the
code it replaced expected the ACK bit to be set and others didn't. I
assumed this was an accidental inconsistency in the code, so wrote
wait_for_chhltd() to always expect ACK to be set. This code appeared to
work correctly for both enumeration of USB keyboards and operation of
USB Ethernet devices. However, this change broke USB Mass Storage (at
least my USB SD card reader). This change reverts to exactly the
original behaviour. I'm not sure why the ACK bit isn't always set
(perhaps a quirk in the USB HW or DWC2 controller), but the code works
this way!

Fixes: 5be4ca7d6ac8 ("usb: dwc2: unify waiting for transfer completion")
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>

drivers/usb/host/dwc2.c

@@ -703,10 +703,9 @@ static int dwc_otg_submit_rh_msg(struct usb_device *dev, unsigned long pipe,
 	return stat;
 }
 
-int wait_for_chhltd(uint32_t *sub, int *toggle)
+int wait_for_chhltd(uint32_t *sub, int *toggle, bool ignore_ack)
 {
-	const uint32_t hcint_comp_hlt_ack = DWC2_HCINT_XFERCOMP |
-		DWC2_HCINT_CHHLTD | DWC2_HCINT_ACK;
+	uint32_t hcint_comp_hlt_ack = DWC2_HCINT_XFERCOMP | DWC2_HCINT_CHHLTD;
 	struct dwc2_hc_regs *hc_regs = &regs->hc_regs[DWC2_HC_CHANNEL];
 	int ret;
 	uint32_t hcint, hctsiz;
@@ -716,6 +715,10 @@ int wait_for_chhltd(uint32_t *sub, int *toggle)
 		return ret;
 
 	hcint = readl(&hc_regs->hcint);
+	if (ignore_ack)
+		hcint &= ~DWC2_HCINT_ACK;
+	else
+		hcint_comp_hlt_ack |= DWC2_HCINT_ACK;
 	if (hcint != hcint_comp_hlt_ack) {
 		debug("%s: Error (HCINT=%08x)\n", __func__, hcint);
 		return -EINVAL;
@@ -739,7 +742,7 @@ static int dwc2_eptype[] = {
 };
 
 int chunk_msg(struct usb_device *dev, unsigned long pipe, int *pid, int in,
-	      void *buffer, int len)
+	      void *buffer, int len, bool ignore_ack)
 {
 	struct dwc2_hc_regs *hc_regs = &regs->hc_regs[DWC2_HC_CHANNEL];
 	int devnum = usb_pipedevice(pipe);
@@ -800,7 +803,7 @@ int chunk_msg(struct usb_device *dev, unsigned long pipe, int *pid, int in,
 				(1 << DWC2_HCCHAR_MULTICNT_OFFSET) |
 				DWC2_HCCHAR_CHEN);
 
-		ret = wait_for_chhltd(&sub, pid);
+		ret = wait_for_chhltd(&sub, pid, ignore_ack);
 		if (ret) {
 			stop_transfer = 1;
 			break;
@@ -839,7 +842,7 @@ int submit_bulk_msg(struct usb_device *dev, unsigned long pipe, void *buffer,
 	}
 
 	return chunk_msg(dev, pipe, &bulk_data_toggle[devnum][ep],
-			 usb_pipein(pipe), buffer, len);
+			 usb_pipein(pipe), buffer, len, true);
 }
 
 int submit_control_msg(struct usb_device *dev, unsigned long pipe, void *buffer,
@@ -857,14 +860,14 @@ int submit_control_msg(struct usb_device *dev, unsigned long pipe, void *buffer,
 	}
 
 	pid = DWC2_HC_PID_SETUP;
-	ret = chunk_msg(dev, pipe, &pid, 0, setup, 8);
+	ret = chunk_msg(dev, pipe, &pid, 0, setup, 8, true);
 	if (ret)
 		return ret;
 
 	if (buffer) {
 		pid = DWC2_HC_PID_DATA1;
 		ret = chunk_msg(dev, pipe, &pid, usb_pipein(pipe), buffer,
-				len);
+				len, false);
 		if (ret)
 			return ret;
 		act_len = dev->act_len;
@@ -879,7 +882,8 @@ int submit_control_msg(struct usb_device *dev, unsigned long pipe, void *buffer,
 		status_direction = 0;
 
 	pid = DWC2_HC_PID_DATA1;
-	ret = chunk_msg(dev, pipe, &pid, status_direction, status_buffer, 0);
+	ret = chunk_msg(dev, pipe, &pid, status_direction, status_buffer, 0,
+		false);
 	if (ret)
 		return ret;