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authorFabrice Gasnier <fabrice.gasnier@st.com>2019-10-01 10:51:09 +0200
committerWolfram Sang <wsa@the-dreams.de>2019-10-24 20:52:17 +0200
commit6d6b0d0d5afc8c4c84b08261260ba11dfa5206f2 (patch)
tree83718c6f89b3dce44c0357ef3025e46a6aa04c19 /drivers/i2c
parent02e64276c6dbcc4c5f39844f33d18180832a58f3 (diff)
i2c: stm32f7: fix a race in slave mode with arbitration loss irq
When in slave mode, an arbitration loss (ARLO) may be detected before the slave had a chance to detect the stop condition (STOPF in ISR). This is seen when two master + slave adapters switch their roles. It provokes the i2c bus to be stuck, busy as SCL line is stretched. - the I2C_SLAVE_STOP event is never generated due to STOPF flag is set but don't generate an irq (race with ARLO irq, STOPIE is masked). STOPF flag remains set until next master xfer (e.g. when STOPIE irq get unmasked). In this case, completion is generated too early: immediately upon new transfer request (then it doesn't send all data). - Some data get stuck in TXDR register. As a consequence, the controller stretches the SCL line: the bus gets busy until a future master transfer triggers the bus busy / recovery mechanism (this can take time... and may never happen at all) So choice is to let the STOPF being detected by the slave isr handler, to properly handle this stop condition. E.g. don't mask IRQs in error handler, when the slave is running. Fixes: 60d609f30de2 ("i2c: i2c-stm32f7: Add slave support") Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-stm32f7.c17
1 files changed, 10 insertions, 7 deletions
diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index c8ce6c8dd404..073bf57a9821 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -1503,7 +1503,7 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
void __iomem *base = i2c_dev->base;
struct device *dev = i2c_dev->dev;
struct stm32_i2c_dma *dma = i2c_dev->dma;
- u32 mask, status;
+ u32 status;
status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
@@ -1528,12 +1528,15 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
f7_msg->result = -EINVAL;
}
- /* Disable interrupts */
- if (stm32f7_i2c_is_slave_registered(i2c_dev))
- mask = STM32F7_I2C_XFER_IRQ_MASK;
- else
- mask = STM32F7_I2C_ALL_IRQ_MASK;
- stm32f7_i2c_disable_irq(i2c_dev, mask);
+ if (!i2c_dev->slave_running) {
+ u32 mask;
+ /* Disable interrupts */
+ if (stm32f7_i2c_is_slave_registered(i2c_dev))
+ mask = STM32F7_I2C_XFER_IRQ_MASK;
+ else
+ mask = STM32F7_I2C_ALL_IRQ_MASK;
+ stm32f7_i2c_disable_irq(i2c_dev, mask);
+ }
/* Disable dma */
if (i2c_dev->use_dma) {