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Subject[PATCH] mmc: sdhci-bcm-kona: Fix locking in sdhci_bcm_kona_sd_card_emulate()
Date
Since sdhci_bcm_kona_sd_card_emulate() can be called from interrupt
context, we must use a spinlock instead of a mutex. This change
essentially restores the way things worked before the change to
mutexes in http://www.spinics.net/lists/linux-mmc/msg20276.html.

Without this change, we see "scheduling while atomic" errors.

Signed-off-by: Markus Mayer <markus.mayer@linaro.org>
---
drivers/mmc/host/sdhci-bcm-kona.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/host/sdhci-bcm-kona.c b/drivers/mmc/host/sdhci-bcm-kona.c
index 7a190fe..f1b0a62 100644
--- a/drivers/mmc/host/sdhci-bcm-kona.c
+++ b/drivers/mmc/host/sdhci-bcm-kona.c
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2013 Broadcom Corporation
+ * Copyright (C) 2013-2014 Broadcom Corporation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
@@ -53,7 +53,7 @@
#define KONA_MMC_AUTOSUSPEND_DELAY (50)

struct sdhci_bcm_kona_dev {
- struct mutex write_lock; /* protect back to back writes */
+ spinlock_t write_lock; /* protect back to back writes */
};


@@ -135,7 +135,7 @@ static int sdhci_bcm_kona_sd_card_emulate(struct sdhci_host *host, int insert)
* insert-removal.
* We keep 20uS
*/
- mutex_lock(&kona_dev->write_lock);
+ spin_lock_bh(&kona_dev->write_lock);
udelay(20);
val = sdhci_readl(host, KONA_SDHOST_CORESTAT);

@@ -153,7 +153,7 @@ static int sdhci_bcm_kona_sd_card_emulate(struct sdhci_host *host, int insert)
val &= ~KONA_SDHOST_CD_SW;
sdhci_writel(host, val, KONA_SDHOST_CORESTAT);
}
- mutex_unlock(&kona_dev->write_lock);
+ spin_unlock_bh(&kona_dev->write_lock);

return 0;
}
@@ -247,7 +247,7 @@ static int sdhci_bcm_kona_probe(struct platform_device *pdev)
pltfm_priv = sdhci_priv(host);

kona_dev = sdhci_pltfm_priv(pltfm_priv);
- mutex_init(&kona_dev->write_lock);
+ spin_lock_init(&kona_dev->write_lock);

mmc_of_parse(host->mmc);

--
1.9.0


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