Re: [RFC PATCH V2 2/2] mmc: allow card to disable tuning

[Erick Shepherd <erick.shepherd@ni.com>]

> Sorry for the slow reply.

> I would expect if there was a general problem with DDR50 SD cards,
> it would have come to light before now.

> Does the card work with any other host controllers with linux?

> If it is specific to a particular kind of card, a card quirk
> could be added, say MMC_QUIRK_BROKEN_DDR50_TUNING

No worries. I have not tested this with other host controllers but
can try to get something set up. This issue has only appeared on
one particular SD card model for us so I would not be surprised if
the I/O errors we see on subsequent tune requests are specific to this
card. I can put together a solution using the card quirk you suggested
if you think that is the best way forward.

My fix is currently spread across two commits, one to return the error
code thrown by the tune request timing out, which prevents the card from
retuning, and this one that prevents the initial card tuning if it has
already failed. Should both parts be controlled by the new card quirk?

Regards,
Erick