On Tue, 31 Aug 2021 at 15:34, Wolfram Sang
<wsa+renesas@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> We have various SanDisk cards which fail tuning to SDR104 unless we
> allow a CMD12 also to be sent to abort a broken tuning. It is true that
> the SD specs do not mention that CMD12 is allowed, but they also don't
> say it is forbidden. And now reality tells that it is needed to make
> some cards work. Other cards I tried did not regress.
>
> If we can agree to allow this for SD, then the problem is now SDIO which
> does not support CMD12. mmc_card_sdio() does not work at this stage
> because host->card is still NULL. Is there any other way to distinguish
> SD and SDIO here?
>
> Not-Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> Hey guys,
>
> so, there are two questions here:
> 1) despite not being mentioned in the spec, do we want to allow CMD12 to
> abort tuning for SD as well?
It sounds like we should give it a try with the CMD12 command for SD
cards as well.
>
> 2) If so, how to make sure not apply it to SDIO but SD only?
For now, I am fine with adding a new bus_ops callback
(->abort_tuning()) and then let mmc_send_abort_tuning() to call it.
I have some additional plans to improve life cycle issues for the
bus_ops, but let's ignore that for now. I can deal with that later.
That said, mmc_send_abort_tuning() should no longer need to take the
opcode as an in-parameter, thus some additional cleanup should be
needed in a few host drivers because of that.
Would that work?
>
> Thanks for your input! Kind regards,
>
> Wolfram
Kind regards
Uffe
>
>
> drivers/mmc/core/mmc_ops.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
> index 973756ed4016..02d378255895 100644
> --- a/drivers/mmc/core/mmc_ops.c
> +++ b/drivers/mmc/core/mmc_ops.c
> @@ -704,14 +704,6 @@ int mmc_send_abort_tuning(struct mmc_host *host, u32 opcode)
> {
> struct mmc_command cmd = {};
>
> - /*
> - * eMMC specification specifies that CMD12 can be used to stop a tuning
> - * command, but SD specification does not, so do nothing unless it is
> - * eMMC.
> - */
> - if (opcode != MMC_SEND_TUNING_BLOCK_HS200)
> - return 0;
> -
> cmd.opcode = MMC_STOP_TRANSMISSION;
> cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
>
> --
> 2.30.2
>
