On 02/12/16 04:21, Masahiro Yamada wrote:
> Some SDHCI-compat controllers support not only SD, but also eMMC,
> but they use different commands for tuning: CMD19 for SD, CMD21 for
> eMMC.
>
> Due to the difference of the underlying mechanism, some controllers
> (at least, the Cadence IP is the case) provide their own registers
> for the eMMC tuning.
>
> This commit will be useful when we want to use platform-specific
> tuning (to support eMMC HS200), but still let it reuse the code
> provided by sdhci_execute_tuning() for SD timing.
>
> If sdhci_ops::platform_execute_tuning receives a timing it does not
> take care of, it can return -ENOTSUPP. Then, it will fall back to
> the SDHCI standard tuning.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> ---
>
> I want to use this in the next commit.
>
> The Cadence IP supports eMMC as well as SD.
>
> The tuning for SD is pretty simple; just set the "Execute Tuning" bit
> of the HOST_CONTROL2 register. So, I can re-use the
> sdhci_execute_tuning().
>
> On the other hand, Cadence provides its own way for eMMC HS200 tuning;
> I need to touch some registers that are specific to Cadence's design.
>
>
> Changes in v3: None
> Changes in v2: None
>
> drivers/mmc/host/sdhci.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 42ef3eb..cdce489 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2004,7 +2004,9 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
> if (host->ops->platform_execute_tuning) {
> spin_unlock_irqrestore(&host->lock, flags);
> err = host->ops->platform_execute_tuning(host, opcode);
> - return err;
> + if (err != -ENOTSUPP)
> + return err;
> + spin_lock_irqsave(&host->lock, flags);
platform_execute_tuning() should not exist. You could export
sdhci_execute_tuning() and then provide your ->execute_tuning() (e.g.
host->mmc_host_ops.execute_tuning = sdhci_cdns_execute_tuning) which can
call sdhci_execute_tuning() if it needs to.
> }
>
> ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
>
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