linux-kernel - [PATCH 3/4] usb: xhci: add XHCI_MISS_CA

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Date:   Fri, 23 Dec 2016 14:52:57 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 3/4] usb: xhci: add XHCI_MISS_CA_EVENT quirk bit

Writing the CMD_RING_ABORT bit in xhci command register should
cause a command completion event with the command completion
code set to command ring stopped. However on some hosts, the
CMD_RING_RUNNING bit is correctly cleared but the completion
event is never sent.

Current xhci driver treats the behavior of "CMD_RING_RUNNING
bit is correctly cleared but the completion event is missed"
as a correct behavior for all hosts. This is different from
that defined in xhci spec. Refer to 4.6.1.2 in xhci spec.

This patch introduces a quirk bit for those quirky hardwares.
For normal hosts, if the command completion for abort command
ring misses, we shall assume that there are larger problems
with the host and assert HCRST.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/usb/host/xhci-ring.c | 17 +++++------------
 drivers/usb/host/xhci.h      |  6 ++++++
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 5935dce..6a23c37 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -345,25 +345,18 @@ static int xhci_abort_cmd_ring(struct xhci_hcd *xhci, unsigned long *flags)
 		 * larger problems with the xHC and assert HCRST.
 		 */
 		temp_64 = xhci_read_64(xhci, &xhci->op_regs->cmd_ring);
-		if (temp_64 & CMD_RING_RUNNING) {
+		if ((temp_64 & CMD_RING_RUNNING) ||
+		    !(xhci->quirks & XHCI_MISS_CA_EVENT)) {
 			xhci_err(xhci,
 				 "Stop command ring failed, maybe the host is dead\n");
 			xhci->xhc_state |= XHCI_STATE_DYING;
 			xhci_halt(xhci);
 			return -ESHUTDOWN;
 		}
-
-		/*
-		 * Writing the CMD_RING_ABORT bit should cause a cmd
-		 * completion event, however on some hosts the bit is
-		 * correctly cleared but the completion event is never
-		 * sent.
-		 */
-		xhci_warn(xhci, "No stop event for abort, ring start fail?\n");
-		xhci_cleanup_command_queue(xhci);
-	} else {
-		xhci_handle_stopped_cmd_ring(xhci, xhci_next_queued_cmd(xhci));
 	}
+
+	xhci_handle_stopped_cmd_ring(xhci, xhci_next_queued_cmd(xhci));
+
 	return 0;
 }
 
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 09fe63f..c550bf0 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1656,6 +1656,12 @@ struct xhci_hcd {
 #define XHCI_SSIC_PORT_UNUSED	(1 << 22)
 #define XHCI_NO_64BIT_SUPPORT	(1 << 23)
 #define XHCI_MISSING_CAS	(1 << 24)
+/*
+ * Writing the CMD_RING_ABORT bit should cause a cmd completion event,
+ * however on some host hw the CMD_RING_RUNNING bit is correctly cleared
+ * but the completion event is never sent.
+ */
+#define XHCI_MISS_CA_EVENT	(1 << 25)
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;
 	/* There are two roothubs to keep track of bus suspend info for */
-- 
2.1.4