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spi: bitbang: Replace spinlock by mutex

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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@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Nicolas Boichat
2015-08-17 11:52:54 +08:00
committed by Mark Brown
parent 6ff33f3902
commit c15f6ed3a1
4 changed files with 12 additions and 15 deletions
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17
drivers/spi/spi-bitbang.c
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@@ -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;