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

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Message-ID: <CAPDyKFrbdL5fYm6o9RA7Eva2sRVydVFWwszEAve1cZYuh5-awQ@mail.gmail.com>
Date: Wed, 3 Jan 2024 11:35:03 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Jorge Ramirez-Ortiz <jorge@...ndries.io>
Cc: adrian.hunter@...el.com, Avri.Altman@....com, christian.loehle@....com, 
	ricardo@...ndries.io, linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org
Subject: Re: [PATCH] mmc: rpmb: do not force a retune before RPMB switch

On Mon, 11 Dec 2023 at 17:55, Jorge Ramirez-Ortiz <jorge@...ndries.io> 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 retune request prior to switching to the RPMB
> partition: mmc_retune_pause() no longer triggers a retune before the
> pause period begins.
>
> 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@...ndries.io>
> Acked-by: Avri Altman <avri.altman@....com>

This seems reasonable, but I would like to see some justification from
a performance point of view in the commit message too.

Moreover, please bump the version number of the patch at each
iteration and add a version summary of what has changed. That helps
the review process.

Kind regards
Uffe

> ---
>  v2:
>     mmc_retune_pause() no longer can trigger a retune.
>     Keeping Avri Altman Acked-by since they are functionally equivalent.
>  v1:
>     modify mmc_retune_pause to optionally trigger a retune.
>
>  drivers/mmc/core/host.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> index 096093f7be00..ed44920e92df 100644
> --- a/drivers/mmc/core/host.c
> +++ b/drivers/mmc/core/host.c
> @@ -119,13 +119,12 @@ 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.
>   */
>  void mmc_retune_pause(struct mmc_host *host)
>  {
>         if (!host->retune_paused) {
>                 host->retune_paused = 1;
> -               mmc_retune_needed(host);
>                 mmc_retune_hold(host);
>         }
>  }
> --
> 2.34.1