Patch "mmc: sdhci: Do not disable interrupts while waiting for clock" has been added to the 4.10-stable tree

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 4.10-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-4.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Adrian Hunter <[email protected]>
Date: Mon, 20 Mar 2017 19:50:29 +0200
Subject: mmc: sdhci: Do not disable interrupts while waiting for clock

From: Adrian Hunter <[email protected]>

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.

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

@@ -1362,7 +1362,9 @@ void sdhci_enable_clk(struct sdhci_host
 			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 [email protected] are

queue-4.10/mmc-sdhci-pci-do-not-disable-interrupts-in-sdhci_intel_set_power.patch queue-4.10/mmc-sdhci-do-not-disable-interrupts-while-waiting-for-clock.patch