patch "xhci: Convert xhci_handshake() to use readl_poll_timeout_atomic()" added to usb-linus

This is a note to let you know that I've just added the patch titled

xhci: Convert xhci_handshake() to use readl_poll_timeout_atomic()

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From f7fac17ca925faa03fc5eb854c081a24075f8bad Mon Sep 17 00:00:00 2001
From: Andrey Smirnov <[email protected]>
Date: Wed, 22 May 2019 14:34:01 +0300
Subject: xhci: Convert xhci_handshake() to use readl_poll_timeout_atomic()

Xhci_handshake() implements the algorithm already captured by readl_poll_timeout_atomic(). Convert the former to use the latter to avoid repetition.

Turned out this patch also fixes a bug on the AMD Stoneyridge platform where usleep(1) sometimes takes over 10ms.
This means a 5 second timeout can easily take over 15 seconds which will trigger the watchdog and reboot the system.

[Add info about patch fixing a bug to commit message -Mathias]

Signed-off-by Andrey Smirnov <[email protected]>

Tested-by Raul E Rangel <[email protected]>

Reviewed-by Raul E Rangel <[email protected]>

Cc <[email protected]>

Signed-off-by Mathias Nyman <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 drivers/usb/host/xhci.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

drivers/usb/host/xhci.c +10 -12

index 048a675bbc52..20db378a6012 100644
@@ -9,6 +9,7 @@
  */
 
 #include <linux/pci.h>
+#include <linux/iopoll.h>
 #include <linux/irq.h>
 #include <linux/log2.h>
 #include <linux/module.h>

@@ -52,7 +53,6 @@ static bool td_on_ring(struct xhci_td *td, struct xhci_ring *ring)
 	return false;
 }
 
-/* TODO: copied from ehci-hcd.c - can this be refactored? */
 /*
  * xhci_handshake - spin reading hc until handshake completes or fails
  * @ptr: address of hc register to be read

@@ -69,18 +69,16 @@ static bool td_on_ring(struct xhci_td *td, struct xhci_ring *ring)
 int xhci_handshake(void __iomem *ptr, u32 mask, u32 done, int usec)
 {
 	u32	result;
+	int	ret;
 
-	do {
-		result = readl(ptr);
-		if (result == ~(u32)0)		/* card removed */
-			return -ENODEV;
-		result &= mask;
-		if (result == done)
-			return 0;
-		udelay(1);
-		usec--;
-	} while (usec > 0);
-	return -ETIMEDOUT;
+	ret = readl_poll_timeout_atomic(ptr, result,
+					(result & mask) == done ||
+					result == U32_MAX,
+					1, usec);
+	if (result == U32_MAX)		/* card removed */
+		return -ENODEV;
+
+	return ret;
 }
 
 /*

Signature · 1 line

2.21.0

Mathias,
Are there any plans to backport this to the other kernels?

Looks like it landed upstream as f7fac17ca925faa03fc5eb854c081a24075f8bad