[PATCH] i2c: aspeed: fix master pending state handling

[Joel Stanley]

On Wed, 9 Oct 2019 at 21:20, Jae Hyun Yoo <jae.hyun.yoo at linux.intel.com> wrote:
>
> In case of master pending state, it should not trigger a master
> command, otherwise data could be corrupted because this H/W shares
> the same data buffer for slave and master operations. It also means
> that H/W command queue handling is unreliable because of the buffer
> sharing issue. To fix this issue, it clears command queue if a
> master command is queued in pending state to use S/W solution
> instead of H/W command queue handling. Also, it refines restarting
> mechanism of the pending master command.
>
> Fixes: 2e57b7cebb98 ("i2c: aspeed: Add multi-master use case support")
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo at linux.intel.com>

Acked-by: Joel Stanley <joel at jms.id.au>

While reviewing I was concerned about the locking in
aspeed_i2c_master_xfer. It's a bit hairy, and I am not convinced it is
without bugs.