[PATCH resend 06/17] xhci: Correct Event Handler Busy flag usage.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



The Event Handler Busy bit in the event ring dequeue pointer is write 1 to
clear.  Fix the interrupt service routine to clear that bit after the
event handler has run.

xhci_set_hc_event_deq() is designed to update the event ring dequeue pointer
without changing any of the four reserved bits in the lower nibble.  The event
handler busy (EHB) bit is write one to clear, so the new value must always
contain a zero in that bit in order to preserve the EHB value.

Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
---
 drivers/usb/host/xhci-hcd.c  |    4 ++--
 drivers/usb/host/xhci-ring.c |    6 +++++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/host/xhci-hcd.c b/drivers/usb/host/xhci-hcd.c
index e157735..2e8e5bf 100644
--- a/drivers/usb/host/xhci-hcd.c
+++ b/drivers/usb/host/xhci-hcd.c
@@ -249,9 +249,9 @@ static void xhci_work(struct xhci_hcd *xhci)
 	/* FIXME this should be a delayed service routine that clears the EHB */
 	xhci_handle_event(xhci);
 
-	/* Clear the event handler busy flag; the event ring should be empty. */
+	/* Clear the event handler busy flag (RW1C); the event ring should be empty. */
 	temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
-	xhci_write_64(xhci, temp_64 & ~ERST_EHB, &xhci->ir_set->erst_dequeue);
+	xhci_write_64(xhci, temp_64 | ERST_EHB, &xhci->ir_set->erst_dequeue);
 	/* Flush posted writes -- FIXME is this necessary? */
 	xhci_readl(xhci, &xhci->ir_set->irq_pending);
 }
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 5dd3b1f..fe9541a 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -248,8 +248,12 @@ void xhci_set_hc_event_deq(struct xhci_hcd *xhci)
 	/* Update HC event ring dequeue pointer */
 	temp = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
 	temp &= ERST_PTR_MASK;
+	/* Don't clear the EHB bit (which is RW1C) because
+	 * there might be more events to service.
+	 */
+	temp &= ~ERST_EHB;
 	if (!in_interrupt())
-		xhci_dbg(xhci, "// Write event ring dequeue pointer\n");
+		xhci_dbg(xhci, "// Write event ring dequeue pointer, preserving EHB bit\n");
 	xhci_write_64(xhci, ((u64) deq & (u64) ~ERST_PTR_MASK) | temp,
 			&xhci->ir_set->erst_dequeue);
 }
-- 
1.5.6.5

--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux