mmc: rpmb: do not force a retune before RPMB switch

Requesting a retune before switching to the RPMB partition has been
observed to cause CRC errors on the RPMB reads (-EILSEQ).

Since RPMB reads can not be retried, the clients would be directly
affected by the errors.

This commit disables the request prior to RPMB switching while allowing
the pause interface to still request a retune before the pause for other
use cases.

This was verified with the sdhci-of-arasan driver (ZynqMP) configured
for HS200 using two separate eMMC cards (DG4064 and 064GB2). In both
cases, the error was easy to reproduce triggering every few tenths of
reads.

Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
Acked-by: Avri Altman <avri.altman@wdc.com>

---
 drivers/mmc/core/block.c | 2 +-
 drivers/mmc/core/host.c  | 7 ++++---
 drivers/mmc/core/host.h  | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

--
2.34.1

On 4/12/23 19:22, Jorge Ramirez-Ortiz wrote:
> Requesting a retune before switching to the RPMB partition has been
> observed to cause CRC errors on the RPMB reads (-EILSEQ).
> 
> Since RPMB reads can not be retried, the clients would be directly
> affected by the errors.
> 
> This commit disables the request prior to RPMB switching while allowing
> the pause interface to still request a retune before the pause for other
> use cases.
> 
> This was verified with the sdhci-of-arasan driver (ZynqMP) configured
> for HS200 using two separate eMMC cards (DG4064 and 064GB2). In both
> cases, the error was easy to reproduce triggering every few tenths of
> reads.
> 
> Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
> Acked-by: Avri Altman <avri.altman@wdc.com>
> 
> ---
>  drivers/mmc/core/block.c | 2 +-
>  drivers/mmc/core/host.c  | 7 ++++---
>  drivers/mmc/core/host.h  | 2 +-
>  3 files changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index f9a5cffa64b1..1d69078ad9b2 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -859,7 +859,7 @@ static int mmc_blk_part_switch_pre(struct mmc_card *card,
>  			if (ret)
>  				return ret;
>  		}
> -		mmc_retune_pause(card->host);
> +		mmc_retune_pause(card->host, false);
>  	}
> 
>  	return ret;
> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> index 096093f7be00..a9b95aaa2235 100644
> --- a/drivers/mmc/core/host.c
> +++ b/drivers/mmc/core/host.c
> @@ -119,13 +119,14 @@ void mmc_retune_enable(struct mmc_host *host)
> 
>  /*
>   * Pause re-tuning for a small set of operations.  The pause begins after the
> - * next command and after first doing re-tuning.
> + * next command and, if retune is set, after first doing re-tuning.
>   */
> -void mmc_retune_pause(struct mmc_host *host)
> +void mmc_retune_pause(struct mmc_host *host, bool retune)
>  {
>  	if (!host->retune_paused) {
>  		host->retune_paused = 1;
> -		mmc_retune_needed(host);
> +		if (retune)
> +			mmc_retune_needed(host);

Better to just drop mmc_retune_needed(host);

>  		mmc_retune_hold(host);
>  	}
>  }
> diff --git a/drivers/mmc/core/host.h b/drivers/mmc/core/host.h
> index 48c4952512a5..321776b52270 100644
> --- a/drivers/mmc/core/host.h
> +++ b/drivers/mmc/core/host.h
> @@ -18,7 +18,7 @@ void mmc_retune_disable(struct mmc_host *host);
>  void mmc_retune_hold(struct mmc_host *host);
>  void mmc_retune_release(struct mmc_host *host);
>  int mmc_retune(struct mmc_host *host);
> -void mmc_retune_pause(struct mmc_host *host);
> +void mmc_retune_pause(struct mmc_host *host, bool retune);
>  void mmc_retune_unpause(struct mmc_host *host);
> 
>  static inline void mmc_retune_clear(struct mmc_host *host)
> --
> 2.34.1