[PATCH] i2c: exynos5: Avoid transaction timeouts due TRANSFER_DONE_AUTO not set

[Wolfram Sang]

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 at osg.samsung.com>
> Reviewed-by: Andrzej Hajda <a.hajda at samsung.com>
> 

Applied to for-current, thanks!

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