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* [PATCH 1/1] usb: xhci: clear EINT bit in status correctly
@ 2016-12-30  5:29 Lu Baolu
  2016-12-30  5:52 ` kbuild test robot
  2016-12-30  6:19 ` kbuild test robot
  0 siblings, 2 replies; 3+ messages in thread
From: Lu Baolu @ 2016-12-30  5:29 UTC (permalink / raw)
  To: Mathias Nyman; +Cc: linux-usb, linux-kernel, Lu Baolu, stable, Felipe Balbi

EINT(Event Interrupt) is a write-1-to-clear type of bit in xhci
status register. It should be cleared by writing a 1. Writing 0
to this bit has no effect.

Xhci driver tries to clear this bit by writing 0 to it. This is
not the right way to go. This patch corrects this by reading the
register first, then clearing all RO/RW1C/RsvZ bits and setting
the clearing bit, and writing back the new value at last.

Xhci spec requires that software that uses EINT shall clear it
prior to clearing any IP flags in section 5.4.2. This is the
reason why this patch is CC'ed stable as well.

Cc: <stable@vger.kernel.org> # v3.14+
CC: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/usb/host/xhci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 1cd5641..18ea6b8 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -721,7 +721,7 @@ void xhci_stop(struct usb_hcd *hcd)
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
 			"// Disabling event ring interrupts");
 	temp = readl(&xhci->op_regs->status);
-	writel(temp & ~STS_EINT, &xhci->op_regs->status);
+	writel(temp & ~0x1fff | STS_EINT, &xhci->op_regs->status);
 	temp = readl(&xhci->ir_set->irq_pending);
 	writel(ER_IRQ_DISABLE(temp), &xhci->ir_set->irq_pending);
 	xhci_print_ir_set(xhci, 0);
@@ -1054,7 +1054,7 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
 
 		xhci_dbg(xhci, "// Disabling event ring interrupts\n");
 		temp = readl(&xhci->op_regs->status);
-		writel(temp & ~STS_EINT, &xhci->op_regs->status);
+		writel(temp & ~0x1fff | STS_EINT, &xhci->op_regs->status);
 		temp = readl(&xhci->ir_set->irq_pending);
 		writel(ER_IRQ_DISABLE(temp), &xhci->ir_set->irq_pending);
 		xhci_print_ir_set(xhci, 0);
-- 
2.1.4

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-12-30  6:20 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-12-30  5:29 [PATCH 1/1] usb: xhci: clear EINT bit in status correctly Lu Baolu
2016-12-30  5:52 ` kbuild test robot
2016-12-30  6:19 ` kbuild test robot

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