From ba272e3bbeaee3b34ca6c616f7ad8d3c65f33f79 Mon Sep 17 00:00:00 2001 From: Katie Dunne Date: Mon, 18 Sep 2017 15:52:40 -0700 Subject: [PATCH] Staging: iio: meter: ade7759: update locking method for write frequency iio_dev->mlock is to be used only by the IIO core for protecting device mode changes between INDIO_DIRECT and INDIO_BUFFER. This patch replaces the use of mlock with the already established buf_lock mutex. Introducing an 'unlocked' spi_write_reg_16 function to be used by ade7759_write_frequency avoids nested locks and maintains atomicity between bus and device frequency changes. Based on the solution found in ade7754 patch here: https://marc.info/?l=linux-iio&m=149086659008991&w=2 Signed-off-by: Katie Dunne Signed-off-by: Jonathan Cameron --- drivers/staging/iio/meter/ade7759.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/drivers/staging/iio/meter/ade7759.c b/drivers/staging/iio/meter/ade7759.c index 7639e90d1c94..cd75f60aded3 100644 --- a/drivers/staging/iio/meter/ade7759.c +++ b/drivers/staging/iio/meter/ade7759.c @@ -60,7 +60,7 @@ /** * struct ade7759_state - device instance specific data * @us: actual spi_device - * @buf_lock: mutex to protect tx and rx + * @buf_lock: mutex to protect tx and rx and write frequency * @tx: transmit buffer * @rx: receive buffer **/ @@ -89,6 +89,20 @@ static int ade7759_spi_write_reg_8(struct device *dev, return ret; } +/*Unlocked version of ade7759_spi_write_reg_16 function */ +static int __ade7759_spi_write_reg_16(struct device *dev, + u8 reg_address, + u16 value) +{ + struct iio_dev *indio_dev = dev_to_iio_dev(dev); + struct ade7759_state *st = iio_priv(indio_dev); + + st->tx[0] = ADE7759_WRITE_REG(reg_address); + st->tx[1] = (value >> 8) & 0xFF; + st->tx[2] = value & 0xFF; + return spi_write(st->us, st->tx, 3); +} + static int ade7759_spi_write_reg_16(struct device *dev, u8 reg_address, u16 value) @@ -98,10 +112,7 @@ static int ade7759_spi_write_reg_16(struct device *dev, struct ade7759_state *st = iio_priv(indio_dev); mutex_lock(&st->buf_lock); - st->tx[0] = ADE7759_WRITE_REG(reg_address); - st->tx[1] = (value >> 8) & 0xFF; - st->tx[2] = value & 0xFF; - ret = spi_write(st->us, st->tx, 3); + ret = __ade7759_spi_write_reg_16(dev, reg_address, value); mutex_unlock(&st->buf_lock); return ret; @@ -429,7 +440,7 @@ static ssize_t ade7759_write_frequency(struct device *dev, if (!val) return -EINVAL; - mutex_lock(&indio_dev->mlock); + mutex_lock(&st->buf_lock); t = 27900 / val; if (t > 0) @@ -447,10 +458,10 @@ static ssize_t ade7759_write_frequency(struct device *dev, reg &= ~(3 << 13); reg |= t << 13; - ret = ade7759_spi_write_reg_16(dev, ADE7759_MODE, reg); + ret = __ade7759_spi_write_reg_16(dev, ADE7759_MODE, reg); out: - mutex_unlock(&indio_dev->mlock); + mutex_unlock(&st->buf_lock); return ret ? ret : len; }