Patch "mmc: sdhci: Do not disable interrupts while waiting for clock" has been added to the 4.4-stable tree

Patch "mmc: sdhci: Do not disable interrupts while waiting for clock" has been added to the 4.4-stable tree

[gregkh]

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

    mmc: sdhci: Do not disable interrupts while waiting for clock

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mmc-sdhci-do-not-disable-interrupts-while-waiting-for-clock.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From e2ebfb2142acefecc2496e71360f50d25726040b Mon Sep 17 00:00:00 2001
From: Adrian Hunter <adrian.hunter@intel.com>
Date: Mon, 20 Mar 2017 19:50:29 +0200
Subject: mmc: sdhci: Do not disable interrupts while waiting for clock

From: Adrian Hunter <adrian.hunter@intel.com>

commit e2ebfb2142acefecc2496e71360f50d25726040b upstream.

Disabling interrupts for even a millisecond can cause problems for some
devices. That can happen when sdhci changes clock frequency because it
waits for the clock to become stable under a spin lock.

The spin lock is not necessary here. Anything that is racing with changes
to the I/O state is already broken. The mmc core already provides
synchronization via "claiming" the host.

Although the spin lock probably should be removed from the code paths that
lead to this point, such a patch would touch too much code to be suitable
for stable trees. Consequently, for this patch, just drop the spin lock
while waiting.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/mmc/host/sdhci.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1274,7 +1274,9 @@ clock_set:
 			return;
 		}
 		timeout--;
-		mdelay(1);
+		spin_unlock_irq(&host->lock);
+		usleep_range(900, 1100);
+		spin_lock_irq(&host->lock);
 	}
 
 	clk |= SDHCI_CLOCK_CARD_EN;


Patches currently in stable-queue which might be from adrian.hunter@intel.com are

queue-4.4/mmc-sdhci-do-not-disable-interrupts-while-waiting-for-clock.patch