Patch "mmc: avoid removing non-removable hosts during suspend" has been added to the 4.14-stable tree

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

mmc: avoid removing non-removable hosts during suspend

to the 4.14-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-avoid-removing-non-removable-hosts-during-suspend.patch
and it can be found in the queue-4.14 subdirectory.

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

From: Daniel Drake <[email protected]>
Date: Tue, 12 Dec 2017 10:49:02 +0000
Subject: mmc: avoid removing non-removable hosts during suspend

From: Daniel Drake <[email protected]>

[ Upstream commit de8dcc3d2c0e08e5068ee1e26fc46415c15e3637 ]

The Weibu F3C MiniPC has an onboard AP6255 module, presenting two SDIO functions on a single MMC host (Bluetooth/btsdio and WiFi/brcmfmac), and the mmc layer correctly detects this as non-removable.

After suspend/resume, the wifi and bluetooth interfaces disappear and do not get probed again.

The conditions here are:

1. During suspend, we reach mmc_pm_notify()

2. mmc_pm_notify() calls mmc_sdio_pre_suspend() to see if we can suspend the SDIO host. However, mmc_sdio_pre_suspend() returns -ENOSYS because btsdio_driver does not have a suspend method.

3. mmc_pm_notify() proceeds to remove the card

4. Upon resume, mmc_rescan() does nothing with this host, because of the rescan_entered check which aims to only scan a non-removable device a single time (i.e. during boot).

Fix the loss of functionality by detecting that we are unable to suspend a non-removable host, so avoid the forced removal in that case. The comment above this function already indicates that this code was only intended for removable devices.

---
 drivers/mmc/core/core.c |    8 ++++++++
 1 file changed, 8 insertions(+)

@@ -2751,6 +2751,14 @@ static int mmc_pm_notify(struct notifier
 		if (!err)
 			break;
 
+		if (!mmc_card_is_removable(host)) {
+			dev_warn(mmc_dev(host),
+				 "pre_suspend failed for non-removable host: "
+				 "%d\n", err);
+			/* Avoid removing non-removable hosts */
+			break;
+		}
+
 		/* Calling bus_ops->remove() with a claimed host can deadlock */
 		host->bus_ops->remove(host);
 		mmc_claim_host(host);

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/mmc-avoid-removing-non-removable-hosts-during-suspend.patch