Re: [PATCH 0/3] mmc: also abort tuning with CMD12 for SD

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On Wed, Sep 15, 2021 at 08:50:21AM +0000, Christian Löhle wrote:
> I did not test the patch but want to make you aware of the comment in dw_mmc:
> /*
> * During UHS tuning sequence, sending the stop
> * command after the response CRC error would
> * throw the system into a confused state
> * causing all future tuning phases to report
> * failure.
> *
> * In such case controller will move into a data
> * transfer state after a response error or
> * response CRC error. Let's let that finish
> * before trying to send a stop, so we'll go to
> * STATE_SENDING_DATA.
> *
> * Although letting the data transfer take place
> * will waste a bit of time (we already know
> * the command was bad), it can't cause any
> * errors since it's possible it would have
> * taken place anyway if this tasklet got
> * delayed. Allowing the transfer to take place
> * avoids races and keeps things simple.
> */
> The message in 46d179525a1f6d16957dcb4624517bc04142b3e7
> does not mention which card was causing problem, unfortunately.

Thank you for the pointer! This is interesting, in deed.

As I understand, it is a limitation of the controller which always goes
into data transfer state even after CRC errors. However, because the
controller driver is not using mmc_send_abort_data(), it will not be
affected by my patch series. My patch series only extends the optional
MMC core helper to be used for SD cards, too, in addition to eMMC.

If I missed something else, please let me know.

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