[PATCH AUTOSEL for 4.4 087/101] mmc: avoid removing non-removable hosts during suspend

Sasha Levin
2018-03-08T05:24:49Z

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

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 5f7d10ba498a..299a83f1ad38 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2791,6 +2791,14 @@ int mmc_pm_notify(struct notifier_block *notify_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);
--
2.14.1