| Message ID | 20170309140533.24618-1-javier@osg.samsung.com |
|---|---|
| State | Accepted |
| Headers | show |
On Thu, Mar 09, 2017 at 11:05:33AM -0300, Javier Martinez Canillas wrote: > After commit 7999eecb7e56 ("i2c: exynos5: fix arbitration lost handling"), > some I2C transactions are failing because the TRANSFER_DONE_AUTO field is > not set in the I2C_TRANS_STATUS register so the i2c->status value is left > to -EINVAL causing the i2c->msg_complete completion to never be signaled. > > For example, when reading the time of an I2C rtc on an Exynos5800 machine: > > $ cat /sys/class/rtc/rtc0/time > [ 25.924594] exynos5-hsi2c 12e10000.i2c: rx timeout > [ 65.028365] max77686-rtc max77802-rtc: Fail to read time reg(-22) > cat: /sys/class/rtc/rtc0/time: Invalid argument > > The Exynos5422 manual states clearly that most I2C_TRANS_STATUS reg bits > (including TRANSFER_DONE_AUTO) are cleared after the register is read. So > reading has side effects and should only be done if HSI2C_INT_I2C was set. > > Fixes: 7999eecb7e56 ("i2c: exynos5: fix arbitration lost handling") > Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com> > Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> > Applied to for-current, thanks!
diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c index cbd93ce0661f..736a82472101 100644 --- a/drivers/i2c/busses/i2c-exynos5.c +++ b/drivers/i2c/busses/i2c-exynos5.c @@ -457,7 +457,6 @@ static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id) int_status = readl(i2c->regs + HSI2C_INT_STATUS); writel(int_status, i2c->regs + HSI2C_INT_STATUS); - trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS); /* handle interrupt related to the transfer status */ if (i2c->variant->hw == HSI2C_EXYNOS7) { @@ -482,11 +481,13 @@ static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id) goto stop; } + trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS); if ((trans_status & HSI2C_MASTER_ST_MASK) == HSI2C_MASTER_ST_LOSE) { i2c->state = -EAGAIN; goto stop; } } else if (int_status & HSI2C_INT_I2C) { + trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS); if (trans_status & HSI2C_NO_DEV_ACK) { dev_dbg(i2c->dev, "No ACK from device\n"); i2c->state = -ENXIO;
After commit 7999eecb7e56 ("i2c: exynos5: fix arbitration lost handling"), some I2C transactions are failing because the TRANSFER_DONE_AUTO field is not set in the I2C_TRANS_STATUS register so the i2c->status value is left to -EINVAL causing the i2c->msg_complete completion to never be signaled. For example, when reading the time of an I2C rtc on an Exynos5800 machine: $ cat /sys/class/rtc/rtc0/time [ 25.924594] exynos5-hsi2c 12e10000.i2c: rx timeout [ 65.028365] max77686-rtc max77802-rtc: Fail to read time reg(-22) cat: /sys/class/rtc/rtc0/time: Invalid argument The Exynos5422 manual states clearly that most I2C_TRANS_STATUS reg bits (including TRANSFER_DONE_AUTO) are cleared after the register is read. So reading has side effects and should only be done if HSI2C_INT_I2C was set. Fixes: 7999eecb7e56 ("i2c: exynos5: fix arbitration lost handling") Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> --- drivers/i2c/busses/i2c-exynos5.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)