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Message-Id: <1439783574-5933-1-git-send-email-drinkcat@chromium.org>
Date: Mon, 17 Aug 2015 11:52:54 +0800
From: Nicolas Boichat <drinkcat@...omium.org>
To: Mark Brown <broonie@...nel.org>
Cc: Kukjin Kim <kgene@...nel.org>,
Krzysztof Kozlowski <k.kozlowski@...sung.com>,
linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org
Subject: [PATCH v2] spi: bitbang: Replace spinlock by mutex
chipselect (in the case of spi-gpio: spi_gpio_chipselect, which
calls gpiod_set_raw_value_cansleep) can sleep, so we should not
hold a spinlock while calling it from spi_bitbang_setup.
This issue was introduced by this commit, which converted spi-gpio
to cansleep variants:
d9dda5a191 "spi: spi-gpio: Use 'cansleep' variants to access GPIO"
Replacing the lock variable by a mutex fixes the issue: This is
safe as all instances where the lock is used are called from
contexts that can sleep.
Finally, update spi-ppc4xx and and spi-s3c24xx to use mutex
functions, as they directly hold the lock for similar purpose.
Signed-off-by: Nicolas Boichat <drinkcat@...omium.org>
---
Going the "safer" way and just replacing the spinlock by a
mutex.
Applies on top of broonie-sound/for-next, and compile-tested on
x86-64/arm (allyesconfig) and ppc44x (defconfig+SPI driver),
and runtime-tested on an arm platform.
Thanks!
drivers/spi/spi-bitbang.c | 17 +++++++----------
drivers/spi/spi-ppc4xx.c | 4 ++--
drivers/spi/spi-s3c24xx.c | 4 ++--
include/linux/spi/spi_bitbang.h | 2 +-
4 files changed, 12 insertions(+), 15 deletions(-)
diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
index 840a498..ef43ef5 100644
--- a/drivers/spi/spi-bitbang.c
+++ b/drivers/spi/spi-bitbang.c
@@ -180,7 +180,6 @@ int spi_bitbang_setup(struct spi_device *spi)
{
struct spi_bitbang_cs *cs = spi->controller_state;
struct spi_bitbang *bitbang;
- unsigned long flags;
bitbang = spi_master_get_devdata(spi->master);
@@ -210,12 +209,12 @@ int spi_bitbang_setup(struct spi_device *spi)
*/
/* deselect chip (low or high) */
- spin_lock_irqsave(&bitbang->lock, flags);
+ mutex_lock(&bitbang->lock);
if (!bitbang->busy) {
bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
ndelay(cs->nsecs);
}
- spin_unlock_irqrestore(&bitbang->lock, flags);
+ mutex_unlock(&bitbang->lock);
return 0;
}
@@ -255,13 +254,12 @@ static int spi_bitbang_bufs(struct spi_device *spi, struct spi_transfer *t)
static int spi_bitbang_prepare_hardware(struct spi_master *spi)
{
struct spi_bitbang *bitbang;
- unsigned long flags;
bitbang = spi_master_get_devdata(spi);
- spin_lock_irqsave(&bitbang->lock, flags);
+ mutex_lock(&bitbang->lock);
bitbang->busy = 1;
- spin_unlock_irqrestore(&bitbang->lock, flags);
+ mutex_unlock(&bitbang->lock);
return 0;
}
@@ -378,13 +376,12 @@ static int spi_bitbang_transfer_one(struct spi_master *master,
static int spi_bitbang_unprepare_hardware(struct spi_master *spi)
{
struct spi_bitbang *bitbang;
- unsigned long flags;
bitbang = spi_master_get_devdata(spi);
- spin_lock_irqsave(&bitbang->lock, flags);
+ mutex_lock(&bitbang->lock);
bitbang->busy = 0;
- spin_unlock_irqrestore(&bitbang->lock, flags);
+ mutex_unlock(&bitbang->lock);
return 0;
}
@@ -427,7 +424,7 @@ int spi_bitbang_start(struct spi_bitbang *bitbang)
if (!master || !bitbang->chipselect)
return -EINVAL;
- spin_lock_init(&bitbang->lock);
+ mutex_init(&bitbang->lock);
if (!master->mode_bits)
master->mode_bits = SPI_CPOL | SPI_CPHA | bitbang->flags;
diff --git a/drivers/spi/spi-ppc4xx.c b/drivers/spi/spi-ppc4xx.c
index 54fb984..dd3d0a2 100644
--- a/drivers/spi/spi-ppc4xx.c
+++ b/drivers/spi/spi-ppc4xx.c
@@ -210,12 +210,12 @@ static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t)
if (in_8(&hw->regs->cdm) != cdm)
out_8(&hw->regs->cdm, cdm);
- spin_lock(&hw->bitbang.lock);
+ mutex_lock(&hw->bitbang.lock);
if (!hw->bitbang.busy) {
hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
/* Need to ndelay here? */
}
- spin_unlock(&hw->bitbang.lock);
+ mutex_unlock(&hw->bitbang.lock);
return 0;
}
diff --git a/drivers/spi/spi-s3c24xx.c b/drivers/spi/spi-s3c24xx.c
index f36bc32..4e7d1bf 100644
--- a/drivers/spi/spi-s3c24xx.c
+++ b/drivers/spi/spi-s3c24xx.c
@@ -198,12 +198,12 @@ static int s3c24xx_spi_setup(struct spi_device *spi)
if (ret)
return ret;
- spin_lock(&hw->bitbang.lock);
+ mutex_lock(&hw->bitbang.lock);
if (!hw->bitbang.busy) {
hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
/* need to ndelay for 0.5 clocktick ? */
}
- spin_unlock(&hw->bitbang.lock);
+ mutex_unlock(&hw->bitbang.lock);
return 0;
}
diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h
index 85578d4..154788e 100644
--- a/include/linux/spi/spi_bitbang.h
+++ b/include/linux/spi/spi_bitbang.h
@@ -4,7 +4,7 @@
#include <linux/workqueue.h>
struct spi_bitbang {
- spinlock_t lock;
+ struct mutex lock;
u8 busy;
u8 use_dma;
u8 flags; /* extra spi->mode support */
--
2.5.0.276.gf5e568e
--
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