Re: [PATCH] mmc: rpmb: do not force a retune before RPMB switch

Adrian Hunter
2023-12-05T20:14:45Z

On 5/12/23 22:12, Adrian Hunter wrote:
> On 4/12/23 17:01, 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).
>
> There are still 2 concerns:
> 1) We don't really know the root cause. Have you determined
> if here are CRC errors in the main partition also?
> 2) Forcing this on everyone
>
> The original idea was that because re-tuning cannot be
> done in RPMB, the need to re-rune in RPMB could be avoided
> by always re-tuning before switching to RPMB and then switching
> straight back. IIRC re-tuning should guarantee at least 4MB
> more I/O without issue.
>
> The alternative to dropping re-tuning in this case could
> be to add a retry loop for MMC_DRV_OP_IOCTL_RPMB if the error
> is -EILSEQ

Actually, you could still do this patch as well because
a CRC error would cause re-tuning before the next retry.

>
>
>>
>> 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>
>> ---
>> 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);
>
> There is still a small chance that re-tuning
> is needed anyway in which case it will still be done.
>
>> }
>> }
>> 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)
>