linux-kernel - [PATCH] mmc: disable card sleep via device-tree

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Date:   Sun, 22 Apr 2018 23:31:26 +0200
From:   Lukasz Majewski <lukma@...x.de>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-kernel@...r.kernel.org
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Fabio Estevam <fabio.estevam@....com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Chanho Min <chanho.min@....com>, devicetree@...r.kernel.org,
        linux-mmc@...r.kernel.org,
        Stanislav Meduna <stanislav.meduna@...control.com>,
        Lukasz Majewski <lukma@...x.de>
Subject: [PATCH] mmc: disable card sleep via device-tree

From: Stanislav Meduna <stanislav.meduna@...control.com>

On a TQMa53 module the mmc_sleep leaves the eMMC card in a state
that the imx53 rom boot code is unable to probe, resulting in
reboot hanging. Add a device tree property to disable sleeping
on suspend.

For TQMa53 modules the exact commit to cause hang after reboot
(v3.10 -> v3.11):
commit 486fdbbc1483 ("mmc: core: Add shutdown callback for (e)MMC bus_ops")

[The exact discussion can be found here:
https://patchwork.kernel.org/patch/8881401/
"i.MX53 restart via watchdog does not work"

Signed-off-by: Stanislav Meduna <stanislav.meduna@...control.com>
Signed-off-by: Lukasz Majewski <lukma@...x.de>
---
 Documentation/devicetree/bindings/mmc/mmc-card.txt | 4 ++++
 drivers/mmc/core/mmc.c                             | 7 +++++--
 include/linux/mmc/card.h                           | 2 +-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/mmc/mmc-card.txt b/Documentation/devicetree/bindings/mmc/mmc-card.txt
index 8d2d71758907..c3ee151edd7c 100644
--- a/Documentation/devicetree/bindings/mmc/mmc-card.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc-card.txt
@@ -12,6 +12,9 @@ Required properties:
 Optional properties:
 -broken-hpi : Use this to indicate that the mmc-card has a broken hpi
               implementation, and that hpi should not be used
+-no-sleep-on-suspend : Do not put the card to sleep when suspending.
+              There are boards with bootloaders that are unable
+              to probe such card when rebooting.
 
 Example:
 
@@ -26,5 +29,6 @@ Example:
 		reg = <0>;
 		compatible = "mmc-card";
 		broken-hpi;
+		no-sleep-on-suspend;
 	};
 };
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 208a762b87ef..a3b74b5c8893 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -381,8 +381,11 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
 	}
 
 	np = mmc_of_find_child_device(card->host, 0);
-	if (np && of_device_is_compatible(np, "mmc-card"))
+	if (np && of_device_is_compatible(np, "mmc-card")) {
 		broken_hpi = of_property_read_bool(np, "broken-hpi");
+		card->no_sleep_on_suspend =
+			of_property_read_bool(np, "no-sleep-on-suspend");
+	}
 	of_node_put(np);
 
 	/*
@@ -1990,7 +1993,7 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
 	if (mmc_can_poweroff_notify(host->card) &&
 		((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend))
 		err = mmc_poweroff_notify(host->card, notify_type);
-	else if (mmc_can_sleep(host->card))
+	else if (mmc_can_sleep(host->card) && !host->card->no_sleep_on_suspend)
 		err = mmc_sleep(host);
 	else if (!mmc_host_is_spi(host))
 		err = mmc_deselect_cards(host);
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 279b39008a33..c64d88e6de3b 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -304,8 +304,8 @@ struct mmc_card {
 	struct dentry		*debugfs_root;
 	struct mmc_part	part[MMC_NUM_PHY_PARTITION]; /* physical partitions */
 	unsigned int    nr_parts;
-
 	unsigned int		bouncesz;	/* Bounce buffer size */
+	bool	no_sleep_on_suspend;
 };
 
 static inline bool mmc_large_sector(struct mmc_card *card)
-- 
2.11.0