Merge tag 'usb-for-v4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb into usb-next

Felipe writes:

usb: changes for v4.16 merge window

Not many changes here, the most important being an improvement for TI's
AM57xx and DRA7xx devices which allows them to disable a metastability
workaround in situations where we know what's going on.

Other than that, we have a set of changes on Renesas UDC to make the
code a little easier to read and maintain while also better supporting
extcon framework.

The u_serial adaptation layer learned to use kfifo instead of cooking
its own FIFO implementation.

DWC3 learned to decode a few more USB requests on the trace output.

6 files changed, 125 insertions, 4 deletions

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 31749c79045f..cd77af3b1565 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -929,6 +929,7 @@ struct dwc2_hsotg {
 	int     irq;
 	struct clk *clk;
 	struct reset_control *reset;
+	struct reset_control *reset_ecc;
 
 	unsigned int queuing_high_bandwidth:1;
 	unsigned int srp_success:1;
@@ -971,6 +972,7 @@ struct dwc2_hsotg {
 	} flags;
 
 	struct list_head non_periodic_sched_inactive;
+	struct list_head non_periodic_sched_waiting;
 	struct list_head non_periodic_sched_active;
 	struct list_head *non_periodic_qh_ptr;
 	struct list_head periodic_sched_inactive;
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 7b6eb0ad513b..a5d72fcd1603 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -659,6 +659,10 @@ static void dwc2_dump_channel_info(struct dwc2_hsotg *hsotg,
 	list_for_each_entry(qh, &hsotg->non_periodic_sched_inactive,
 			    qh_list_entry)
 		dev_dbg(hsotg->dev, "    %p\n", qh);
+	dev_dbg(hsotg->dev, "  NP waiting sched:\n");
+	list_for_each_entry(qh, &hsotg->non_periodic_sched_waiting,
+			    qh_list_entry)
+		dev_dbg(hsotg->dev, "    %p\n", qh);
 	dev_dbg(hsotg->dev, "  NP active sched:\n");
 	list_for_each_entry(qh, &hsotg->non_periodic_sched_active,
 			    qh_list_entry)
@@ -1818,6 +1822,7 @@ static void dwc2_qh_list_free(struct dwc2_hsotg *hsotg,
 static void dwc2_kill_all_urbs(struct dwc2_hsotg *hsotg)
 {
 	dwc2_kill_urbs_in_qh_list(hsotg, &hsotg->non_periodic_sched_inactive);
+	dwc2_kill_urbs_in_qh_list(hsotg, &hsotg->non_periodic_sched_waiting);
 	dwc2_kill_urbs_in_qh_list(hsotg, &hsotg->non_periodic_sched_active);
 	dwc2_kill_urbs_in_qh_list(hsotg, &hsotg->periodic_sched_inactive);
 	dwc2_kill_urbs_in_qh_list(hsotg, &hsotg->periodic_sched_ready);
@@ -4998,6 +5003,7 @@ static void dwc2_hcd_free(struct dwc2_hsotg *hsotg)
 
 	/* Free memory for QH/QTD lists */
 	dwc2_qh_list_free(hsotg, &hsotg->non_periodic_sched_inactive);
+	dwc2_qh_list_free(hsotg, &hsotg->non_periodic_sched_waiting);
 	dwc2_qh_list_free(hsotg, &hsotg->non_periodic_sched_active);
 	dwc2_qh_list_free(hsotg, &hsotg->periodic_sched_inactive);
 	dwc2_qh_list_free(hsotg, &hsotg->periodic_sched_ready);
@@ -5159,6 +5165,7 @@ int dwc2_hcd_init(struct dwc2_hsotg *hsotg)
 
 	/* Initialize the non-periodic schedule */
 	INIT_LIST_HEAD(&hsotg->non_periodic_sched_inactive);
+	INIT_LIST_HEAD(&hsotg->non_periodic_sched_waiting);
 	INIT_LIST_HEAD(&hsotg->non_periodic_sched_active);
 
 	/* Initialize the periodic schedule */
diff --git a/drivers/usb/dwc2/hcd.h b/drivers/usb/dwc2/hcd.h
index 78e9e01051b5..ad60e46e66e1 100644
--- a/drivers/usb/dwc2/hcd.h
+++ b/drivers/usb/dwc2/hcd.h
@@ -314,12 +314,16 @@ struct dwc2_hs_transfer_time {
  *                      descriptor and indicates original XferSize value for the
  *                      descriptor
  * @unreserve_timer:    Timer for releasing periodic reservation.
+ * @wait_timer:         Timer used to wait before re-queuing.
  * @dwc2_tt:            Pointer to our tt info (or NULL if no tt).
  * @ttport:             Port number within our tt.
  * @tt_buffer_dirty     True if clear_tt_buffer_complete is pending
  * @unreserve_pending:  True if we planned to unreserve but haven't yet.
  * @schedule_low_speed: True if we have a low/full speed component (either the
  *			host is in low/full speed mode or do_split).
+ * @want_wait:          We should wait before re-queuing; only matters for non-
+ *                      periodic transfers and is ignored for periodic ones.
+ * @wait_timer_cancel:  Set to true to cancel the wait_timer.
  *
  * A Queue Head (QH) holds the static characteristics of an endpoint and
  * maintains a list of transfers (QTDs) for that endpoint. A QH structure may
@@ -354,11 +358,14 @@ struct dwc2_qh {
 	u32 desc_list_sz;
 	u32 *n_bytes;
 	struct timer_list unreserve_timer;
+	struct timer_list wait_timer;
 	struct dwc2_tt *dwc_tt;
 	int ttport;
 	unsigned tt_buffer_dirty:1;
 	unsigned unreserve_pending:1;
 	unsigned schedule_low_speed:1;
+	unsigned want_wait:1;
+	unsigned wait_timer_cancel:1;
 };
 
 /**
@@ -389,6 +396,7 @@ struct dwc2_qh {
  * @n_desc:             Number of DMA descriptors for this QTD
  * @isoc_frame_index_last: Last activated frame (packet) index, used in
  *                      descriptor DMA mode only
+ * @num_naks:           Number of NAKs received on this QTD.
  * @urb:                URB for this transfer
  * @qh:                 Queue head for this QTD
  * @qtd_list_entry:     For linking to the QH's list of QTDs
@@ -419,6 +427,7 @@ struct dwc2_qtd {
 	u8 error_count;
 	u8 n_desc;
 	u16 isoc_frame_index_last;
+	u16 num_naks;
 	struct dwc2_hcd_urb *urb;
 	struct dwc2_qh *qh;
 	struct list_head qtd_list_entry;
diff --git a/drivers/usb/dwc2/hcd_intr.c b/drivers/usb/dwc2/hcd_intr.c
index 916d991b96b8..a5dfd9d8bd9a 100644
--- a/drivers/usb/dwc2/hcd_intr.c
+++ b/drivers/usb/dwc2/hcd_intr.c
@@ -53,6 +53,12 @@
 #include "core.h"
 #include "hcd.h"
 
+/*
+ * If we get this many NAKs on a split transaction we'll slow down
+ * retransmission.  A 1 here means delay after the first NAK.
+ */
+#define DWC2_NAKS_BEFORE_DELAY		3
+
 /* This function is for debug only */
 static void dwc2_track_missed_sofs(struct dwc2_hsotg *hsotg)
 {
@@ -1201,11 +1207,25 @@ static void dwc2_hc_nak_intr(struct dwc2_hsotg *hsotg,
 	/*
 	 * Handle NAK for IN/OUT SSPLIT/CSPLIT transfers, bulk, control, and
 	 * interrupt. Re-start the SSPLIT transfer.
+	 *
+	 * Normally for non-periodic transfers we'll retry right away, but to
+	 * avoid interrupt storms we'll wait before retrying if we've got
+	 * several NAKs. If we didn't do this we'd retry directly from the
+	 * interrupt handler and could end up quickly getting another
+	 * interrupt (another NAK), which we'd retry.
+	 *
+	 * Note that in DMA mode software only gets involved to re-send NAKed
+	 * transfers for split transactions, so we only need to apply this
+	 * delaying logic when handling splits. In non-DMA mode presumably we
+	 * might want a similar delay if someone can demonstrate this problem
+	 * affects that code path too.
 	 */
 	if (chan->do_split) {
 		if (chan->complete_split)
 			qtd->error_count = 0;
 		qtd->complete_split = 0;
+		qtd->num_naks++;
+		qtd->qh->want_wait = qtd->num_naks >= DWC2_NAKS_BEFORE_DELAY;
 		dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_NAK);
 		goto handle_nak_done;
 	}
diff --git a/drivers/usb/dwc2/hcd_queue.c b/drivers/usb/dwc2/hcd_queue.c
index fcd1676c7f0b..e34ad5e65350 100644
--- a/drivers/usb/dwc2/hcd_queue.c
+++ b/drivers/usb/dwc2/hcd_queue.c
@@ -58,6 +58,9 @@
 /* Wait this long before releasing periodic reservation */
 #define DWC2_UNRESERVE_DELAY (msecs_to_jiffies(5))
 
+/* If we get a NAK, wait this long before retrying */
+#define DWC2_RETRY_WAIT_DELAY (msecs_to_jiffies(1))
+
 /**
  * dwc2_periodic_channel_available() - Checks that a channel is available for a
  * periodic transfer
@@ -1441,6 +1444,55 @@ static void dwc2_deschedule_periodic(struct dwc2_hsotg *hsotg,
 }
 
 /**
+ * dwc2_wait_timer_fn() - Timer function to re-queue after waiting
+ *
+ * As per the spec, a NAK indicates that "a function is temporarily unable to
+ * transmit or receive data, but will eventually be able to do so without need
+ * of host intervention".
+ *
+ * That means that when we encounter a NAK we're supposed to retry.
+ *
+ * ...but if we retry right away (from the interrupt handler that saw the NAK)
+ * then we can end up with an interrupt storm (if the other side keeps NAKing
+ * us) because on slow enough CPUs it could take us longer to get out of the
+ * interrupt routine than it takes for the device to send another NAK.  That
+ * leads to a constant stream of NAK interrupts and the CPU locks.
+ *
+ * ...so instead of retrying right away in the case of a NAK we'll set a timer
+ * to retry some time later.  This function handles that timer and moves the
+ * qh back to the "inactive" list, then queues transactions.
+ *
+ * @t: Pointer to wait_timer in a qh.
+ */
+static void dwc2_wait_timer_fn(struct timer_list *t)
+{
+	struct dwc2_qh *qh = from_timer(qh, t, wait_timer);
+	struct dwc2_hsotg *hsotg = qh->hsotg;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hsotg->lock, flags);
+
+	/*
+	 * We'll set wait_timer_cancel to true if we want to cancel this
+	 * operation in dwc2_hcd_qh_unlink().
+	 */
+	if (!qh->wait_timer_cancel) {
+		enum dwc2_transaction_type tr_type;
+
+		qh->want_wait = false;
+
+		list_move(&qh->qh_list_entry,
+			  &hsotg->non_periodic_sched_inactive);
+
+		tr_type = dwc2_hcd_select_transactions(hsotg);
+		if (tr_type != DWC2_TRANSACTION_NONE)
+			dwc2_hcd_queue_transactions(hsotg, tr_type);
+	}
+
+	spin_unlock_irqrestore(&hsotg->lock, flags);
+}
+
+/**
  * dwc2_qh_init() - Initializes a QH structure
  *
  * @hsotg: The HCD state structure for the DWC OTG controller
@@ -1468,6 +1520,7 @@ static void dwc2_qh_init(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh,
 	/* Initialize QH */
 	qh->hsotg = hsotg;
 	timer_setup(&qh->unreserve_timer, dwc2_unreserve_timer_fn, 0);
+	timer_setup(&qh->wait_timer, dwc2_wait_timer_fn, 0);
 	qh->ep_type = ep_type;
 	qh->ep_is_in = ep_is_in;
 
@@ -1628,6 +1681,16 @@ void dwc2_hcd_qh_free(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
 		dwc2_do_unreserve(hsotg, qh);
 		spin_unlock_irqrestore(&hsotg->lock, flags);
 	}
+
+	/*
+	 * We don't have the lock so we can safely wait until the wait timer
+	 * finishes.  Of course, at this point in time we'd better have set
+	 * wait_timer_active to false so if this timer was still pending it
+	 * won't do anything anyway, but we want it to finish before we free
+	 * memory.
+	 */
+	del_timer_sync(&qh->wait_timer);
+
 	dwc2_host_put_tt_info(hsotg, qh->dwc_tt);
 
 	if (qh->desc_list)
@@ -1663,9 +1726,16 @@ int dwc2_hcd_qh_add(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
 		qh->start_active_frame = hsotg->frame_number;
 		qh->next_active_frame = qh->start_active_frame;
 
-		/* Always start in inactive schedule */
-		list_add_tail(&qh->qh_list_entry,
-			      &hsotg->non_periodic_sched_inactive);
+		if (qh->want_wait) {
+			list_add_tail(&qh->qh_list_entry,
+				      &hsotg->non_periodic_sched_waiting);
+			qh->wait_timer_cancel = false;
+			mod_timer(&qh->wait_timer,
+				  jiffies + DWC2_RETRY_WAIT_DELAY + 1);
+		} else {
+			list_add_tail(&qh->qh_list_entry,
+				      &hsotg->non_periodic_sched_inactive);
+		}
 		return 0;
 	}
 
@@ -1695,6 +1765,9 @@ void dwc2_hcd_qh_unlink(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
 
 	dev_vdbg(hsotg->dev, "%s()\n", __func__);
 
+	/* If the wait_timer is pending, this will stop it from acting */
+	qh->wait_timer_cancel = true;
+
 	if (list_empty(&qh->qh_list_entry))
 		/* QH is not in a schedule */
 		return;
@@ -1903,7 +1976,7 @@ void dwc2_hcd_qh_deactivate(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh,
 	if (dwc2_qh_is_non_per(qh)) {
 		dwc2_hcd_qh_unlink(hsotg, qh);
 		if (!list_empty(&qh->qtd_list))
-			/* Add back to inactive non-periodic schedule */
+			/* Add back to inactive/waiting non-periodic schedule */
 			dwc2_hcd_qh_add(hsotg, qh);
 		return;
 	}
diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index 3e26550d13dd..4703478f702f 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -221,6 +221,15 @@ static int dwc2_lowlevel_hw_init(struct dwc2_hsotg *hsotg)
 
 	reset_control_deassert(hsotg->reset);
 
+	hsotg->reset_ecc = devm_reset_control_get_optional(hsotg->dev, "dwc2-ecc");
+	if (IS_ERR(hsotg->reset_ecc)) {
+		ret = PTR_ERR(hsotg->reset_ecc);
+		dev_err(hsotg->dev, "error getting reset control for ecc %d\n", ret);
+		return ret;
+	}
+
+	reset_control_deassert(hsotg->reset_ecc);
+
 	/* Set default UTMI width */
 	hsotg->phyif = GUSBCFG_PHYIF16;
 
@@ -319,6 +328,7 @@ static int dwc2_driver_remove(struct platform_device *dev)
 		dwc2_lowlevel_hw_disable(hsotg);
 
 	reset_control_assert(hsotg->reset);
+	reset_control_assert(hsotg->reset_ecc);
 
 	return 0;
 }