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From:   Martin Kepplinger <martin.kepplinger@puri.sm>
To:     mathias.nyman@intel.com, gregkh@linuxfoundation.org
Cc:     kernel@puri.sm, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Martin Kepplinger <martin.kepplinger@puri.sm>
Subject: [PATCH] usb: xhci: make XHCI_STOP_EP_CMD_TIMEOUT a module parameter
Date:   Fri,  4 Mar 2022 12:30:57 +0100
Message-Id: <20220304113057.1477958-1-martin.kepplinger@puri.sm>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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On the Librem 5 imx8mq system we've seen the stop endpoint command
time out regularly which results in the hub dying.

While on the one hand we see "Port resume timed out, port 1-1: 0xfe3"
before this and on the other hand driver-comments suggest that the driver
might be able to recover instead of dying here, Sarah seemed to have a
workaround for this particulator problem in mind already:

Make it a module parameter. So while it might not be the root cause for
the problem, do this to give users a workaround.

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
---
 drivers/usb/host/xhci-ring.c | 2 +-
 drivers/usb/host/xhci.c      | 8 +++++++-
 drivers/usb/host/xhci.h      | 3 +--
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index d0b6806275e0..e631d408e6b2 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1133,7 +1133,7 @@ static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id,
 				xhci_stop_watchdog_timer_in_irq(xhci, ep);
 
 			mod_timer(&ep->stop_cmd_timer,
-				  jiffies + XHCI_STOP_EP_CMD_TIMEOUT * HZ);
+				  jiffies + xhci->stop_ep_cmd_timeout * HZ);
 			xhci_queue_stop_endpoint(xhci, command, slot_id, ep_index, 0);
 			xhci_ring_cmd_db(xhci);
 
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index a1c781f70d02..37fd05e75dcf 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -37,6 +37,11 @@ static unsigned long long quirks;
 module_param(quirks, ullong, S_IRUGO);
 MODULE_PARM_DESC(quirks, "Bit flags for quirks to be enabled as default");
 
+static unsigned int stop_ep_cmd_timeout = 5;
+module_param(stop_ep_cmd_timeout, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(stop_ep_cmd_timeout,
+		 "Stop endpoint command timeout (secs) for URB cancel watchdog. default=5");
+
 static bool td_on_ring(struct xhci_td *td, struct xhci_ring *ring)
 {
 	struct xhci_segment *seg = ring->first_seg;
@@ -1849,7 +1854,7 @@ static int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
 		}
 		ep->ep_state |= EP_STOP_CMD_PENDING;
 		ep->stop_cmd_timer.expires = jiffies +
-			XHCI_STOP_EP_CMD_TIMEOUT * HZ;
+			xhci->stop_ep_cmd_timeout * HZ;
 		add_timer(&ep->stop_cmd_timer);
 		xhci_queue_stop_endpoint(xhci, command, urb->dev->slot_id,
 					 ep_index, 0);
@@ -5288,6 +5293,7 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
 		xhci->hcc_params2 = readl(&xhci->cap_regs->hcc_params2);
 
 	xhci->quirks |= quirks;
+	xhci->stop_ep_cmd_timeout = stop_ep_cmd_timeout;
 
 	get_quirks(dev, xhci);
 
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 8a0026ee9524..80c9ced4a276 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1674,8 +1674,6 @@ struct urb_priv {
 #define	ERST_NUM_SEGS	1
 /* Poll every 60 seconds */
 #define	POLL_TIMEOUT	60
-/* Stop endpoint command timeout (secs) for URB cancellation watchdog timer */
-#define XHCI_STOP_EP_CMD_TIMEOUT	5
 /* XXX: Make these module parameters */
 
 struct s3_save {
@@ -1899,6 +1897,7 @@ struct xhci_hcd {
 #define XHCI_BROKEN_D3COLD	BIT_ULL(41)
 #define XHCI_EP_CTX_BROKEN_DCS	BIT_ULL(42)
 
+	unsigned int		stop_ep_cmd_timeout;
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;
 	struct xhci_port	*hw_ports;
-- 
2.30.2