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 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: mmc-avoid-removing-non-removable-hosts-during-suspend.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 foo@baz Thu Mar 22 14:57:33 CET 2018

From: Daniel Drake drake@endlessm.com Date: Tue, 12 Dec 2017 10:49:02 +0000 Subject: mmc: avoid removing non-removable hosts during suspend

From: Daniel Drake drake@endlessm.com

[ 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.

Signed-off-by: Daniel Drake drake@endlessm.com Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/mmc/core/core.c | 8 ++++++++ 1 file changed, 8 insertions(+)

--- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -2791,6 +2791,14 @@ int mmc_pm_notify(struct notifier_block 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 drake@endlessm.com are

queue-4.4/mmc-avoid-removing-non-removable-hosts-during-suspend.patch