usb: Keep async schedule running only across mass storage xfers

Rather than keeping the asynchronous schedule running always, keep it
running only across USB mass storage transfers for now, as it seems
that keeping it running all the time interferes with certain control
transfers during device enumeration.

Note that running the async schedule all the time should not be an
issue, especially on EHCI HCD, as that one implements most of the
transfers using async schedule.

Note that we have usb_disable_asynch(), which however is utterly broken.
The usb_disable_asynch() blocks the USB core from doing async transfers
by setting a global flag. The async schedule should however be disabled
per USB controller. Moreover, setting a global flag does not prevent the
controller from using the async schedule, which e.g. the EHCI HCD does.

This patch implements additional callback to the controller, which
permits it to lock the async schedule and keep it running across
multiple transfers. Once the schedule is unlocked, it must also be
disabled. This thus prevents the async schedule from running outside
of the USB mass storage transfers.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Lukasz Majewski <lukma@denx.de>
Cc: Tom Rini <trini@konsulko.com>
Tested-by: Tom Rini <trini@konsulko.com> [omap3_beagle, previously failing]

common/usb.c

@@ -172,6 +172,12 @@ int usb_detect_change(void)
 	return change;
 }
 
+/* Lock or unlock async schedule on the controller */
+__weak int usb_lock_async(struct usb_device *dev, int lock)
+{
+	return 0;
+}
+
 /*
  * disables the asynch behaviour of the control message. This is used for data
  * transfers that uses the exclusiv access to the control and bulk messages.

common/usb_storage.c

@@ -1157,6 +1157,7 @@ static unsigned long usb_stor_read(struct blk_desc *block_dev, lbaint_t blknr,
 	ss = (struct us_data *)udev->privptr;
 
 	usb_disable_asynch(1); /* asynch transfer not allowed */
+	usb_lock_async(udev, 1);
 	srb->lun = block_dev->lun;
 	buf_addr = (uintptr_t)buffer;
 	start = blknr;
@@ -1195,6 +1196,7 @@ retry_it:
 	debug("usb_read: end startblk " LBAF ", blccnt %x buffer %lx\n",
 	      start, smallblks, buf_addr);
 
+	usb_lock_async(udev, 0);
 	usb_disable_asynch(0); /* asynch transfer allowed */
 	if (blkcnt >= ss->max_xfer_blk)
 		debug("\n");
@@ -1239,6 +1241,7 @@ static unsigned long usb_stor_write(struct blk_desc *block_dev, lbaint_t blknr,
 	ss = (struct us_data *)udev->privptr;
 
 	usb_disable_asynch(1); /* asynch transfer not allowed */
+	usb_lock_async(udev, 1);
 
 	srb->lun = block_dev->lun;
 	buf_addr = (uintptr_t)buffer;
@@ -1280,6 +1283,7 @@ retry_it:
 	debug("usb_write: end startblk " LBAF ", blccnt %x buffer %lx\n",
 	      start, smallblks, buf_addr);
 
+	usb_lock_async(udev, 0);
 	usb_disable_asynch(0); /* asynch transfer allowed */
 	if (blkcnt >= ss->max_xfer_blk)
 		debug("\n");

drivers/usb/host/ehci-hcd.c

@@ -298,6 +298,51 @@ static void ehci_update_endpt2_dev_n_port(struct usb_device *udev,
 				     QH_ENDPT2_HUBADDR(hubaddr));
 }
 
+static int ehci_enable_async(struct ehci_ctrl *ctrl)
+{
+	u32 cmd;
+	int ret;
+
+	/* Enable async. schedule. */
+	cmd = ehci_readl(&ctrl->hcor->or_usbcmd);
+	if (cmd & CMD_ASE)
+		return 0;
+
+	cmd |= CMD_ASE;
+	ehci_writel(&ctrl->hcor->or_usbcmd, cmd);
+
+	ret = handshake((uint32_t *)&ctrl->hcor->or_usbsts, STS_ASS, STS_ASS,
+			100 * 1000);
+	if (ret < 0)
+		printf("EHCI fail timeout STS_ASS set\n");
+
+	return ret;
+}
+
+static int ehci_disable_async(struct ehci_ctrl *ctrl)
+{
+	u32 cmd;
+	int ret;
+
+	if (ctrl->async_locked)
+		return 0;
+
+	/* Disable async schedule. */
+	cmd = ehci_readl(&ctrl->hcor->or_usbcmd);
+	if (!(cmd & CMD_ASE))
+		return 0;
+
+	cmd &= ~CMD_ASE;
+	ehci_writel(&ctrl->hcor->or_usbcmd, cmd);
+
+	ret = handshake((uint32_t *)&ctrl->hcor->or_usbsts, STS_ASS, 0,
+			100 * 1000);
+	if (ret < 0)
+		printf("EHCI fail timeout STS_ASS reset\n");
+
+	return ret;
+}
+
 static int
 ehci_submit_async(struct usb_device *dev, unsigned long pipe, void *buffer,
 		   int length, struct devrequest *req)
@@ -311,7 +356,6 @@ ehci_submit_async(struct usb_device *dev, unsigned long pipe, void *buffer,
 	uint32_t *tdp;
 	uint32_t endpt, maxpacket, token, usbsts, qhtoken;
 	uint32_t c, toggle;
-	uint32_t cmd;
 	int timeout;
 	int ret = 0;
 	struct ehci_ctrl *ctrl = ehci_get_ctrl(dev);
@@ -556,19 +600,9 @@ ehci_submit_async(struct usb_device *dev, unsigned long pipe, void *buffer,
 	usbsts = ehci_readl(&ctrl->hcor->or_usbsts);
 	ehci_writel(&ctrl->hcor->or_usbsts, (usbsts & 0x3f));
 
-	/* Enable async. schedule. */
-	cmd = ehci_readl(&ctrl->hcor->or_usbcmd);
-	if (!(cmd & CMD_ASE)) {
-		cmd |= CMD_ASE;
-		ehci_writel(&ctrl->hcor->or_usbcmd, cmd);
-
-		ret = handshake((uint32_t *)&ctrl->hcor->or_usbsts, STS_ASS, STS_ASS,
-				100 * 1000);
-		if (ret < 0) {
-			printf("EHCI fail timeout STS_ASS set\n");
+	ret = ehci_enable_async(ctrl);
+	if (ret)
 		goto fail;
-		}
-	}
 
 	/* Wait for TDs to be processed. */
 	ts = get_timer(0);
@@ -611,6 +645,10 @@ ehci_submit_async(struct usb_device *dev, unsigned long pipe, void *buffer,
 	if (QT_TOKEN_GET_STATUS(token) & QT_TOKEN_STATUS_ACTIVE)
 		printf("EHCI timed out on TD - token=%#x\n", token);
 
+	ret = ehci_disable_async(ctrl);
+	if (ret)
+		goto fail;
+
 	if (!(QT_TOKEN_GET_STATUS(qhtoken) & QT_TOKEN_STATUS_ACTIVE)) {
 		debug("TOKEN=%#x\n", qhtoken);
 		switch (QT_TOKEN_GET_STATUS(qhtoken) &
@@ -1512,6 +1550,16 @@ static int _ehci_submit_int_msg(struct usb_device *dev, unsigned long pipe,
 	return result;
 }
 
+static int _ehci_lock_async(struct ehci_ctrl *ctrl, int lock)
+{
+	ctrl->async_locked = lock;
+
+	if (lock)
+		return 0;
+
+	return ehci_disable_async(ctrl);
+}
+
 #if !CONFIG_IS_ENABLED(DM_USB)
 int submit_bulk_msg(struct usb_device *dev, unsigned long pipe,
 			    void *buffer, int length)
@@ -1549,6 +1597,13 @@ int destroy_int_queue(struct usb_device *dev, struct int_queue *queue)
 {
 	return _ehci_destroy_int_queue(dev, queue);
 }
+
+int usb_lock_async(struct usb_device *dev, int lock)
+{
+	struct ehci_ctrl *ctrl = ehci_get_ctrl(dev);
+
+	return _ehci_lock_async(ctrl, lock);
+}
 #endif
 
 #if CONFIG_IS_ENABLED(DM_USB)
@@ -1612,6 +1667,13 @@ static int ehci_get_max_xfer_size(struct udevice *dev, size_t *size)
 	return 0;
 }
 
+static int ehci_lock_async(struct udevice *dev, int lock)
+{
+	struct ehci_ctrl *ctrl = dev_get_priv(dev);
+
+	return _ehci_lock_async(ctrl, lock);
+}
+
 int ehci_register(struct udevice *dev, struct ehci_hccr *hccr,
 		  struct ehci_hcor *hcor, const struct ehci_ops *ops,
 		  uint tweaks, enum usb_init_type init)
@@ -1678,6 +1740,7 @@ struct dm_usb_ops ehci_usb_ops = {
 	.poll_int_queue = ehci_poll_int_queue,
 	.destroy_int_queue = ehci_destroy_int_queue,
 	.get_max_xfer_size  = ehci_get_max_xfer_size,
+	.lock_async = ehci_lock_async,
 };
 
 #endif

drivers/usb/host/ehci.h

@@ -255,6 +255,7 @@ struct ehci_ctrl {
 	int periodic_schedules;
 	int ntds;
 	bool has_fsl_erratum_a005275;	/* Freescale HS silicon quirk */
+	bool async_locked;
 	struct ehci_ops ops;
 	void *priv;	/* client's private data */
 };

drivers/usb/host/usb-uclass.c

@@ -22,6 +22,17 @@ struct usb_uclass_priv {
 	int companion_device_count;
 };
 
+int usb_lock_async(struct usb_device *udev, int lock)
+{
+	struct udevice *bus = udev->controller_dev;
+	struct dm_usb_ops *ops = usb_get_ops(bus);
+
+	if (!ops->lock_async)
+		return -ENOSYS;
+
+	return ops->lock_async(bus, lock);
+}
+
 int usb_disable_asynch(int disable)
 {
 	int old_value = asynch_allowed;

include/usb.h

@@ -269,6 +269,7 @@ int usb_bulk_msg(struct usb_device *dev, unsigned int pipe,
 			void *data, int len, int *actual_length, int timeout);
 int usb_int_msg(struct usb_device *dev, unsigned long pipe,
 		void *buffer, int transfer_len, int interval, bool nonblock);
+int usb_lock_async(struct usb_device *dev, int lock);
 int usb_disable_asynch(int disable);
 int usb_maxpacket(struct usb_device *dev, unsigned long pipe);
 int usb_get_configuration_no(struct usb_device *dev, int cfgno,
@@ -791,6 +792,16 @@ struct dm_usb_ops {
 	 * in a USB transfer. USB class driver needs to be aware of this.
 	 */
 	int (*get_max_xfer_size)(struct udevice *bus, size_t *size);
+
+	/**
+	 * lock_async() - Keep async schedule after a transfer
+	 *
+	 * It may be desired to keep the asynchronous schedule running even
+	 * after a transfer finishes, usually when doing multiple transfers
+	 * back-to-back. This callback allows signalling the USB controller
+	 * driver to do just that.
+	 */
+	int (*lock_async)(struct udevice *udev, int lock);
 };
 
 #define usb_get_ops(dev)	((struct dm_usb_ops *)(dev)->driver->ops)