linux-kernel - Re: [PATCH] Revert "mmc: meson-gx: include tx phase in the tuning process"

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Date:   Wed, 14 Feb 2018 11:38:34 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Jerome Brunet <jbrunet@...libre.com>
Cc:     Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Revert "mmc: meson-gx: include tx phase in the tuning process"

On 12 February 2018 at 14:13, Jerome Brunet <jbrunet@...libre.com> wrote:
> This reverts commit 0a44697627d17a66d7dc98f17aeca07ca79c5c20.
>
> This commit was initially intended to fix problems with hs200 and hs400
> on some boards, mainly the odroid-c2. The OC2 (Rev 0.2) I have performs
> well in this modes, so I could not confirm these issues.
>
> We've had several reports about the issues being still present on (some)
> OC2, so apparently, this change does not do what it was supposed to do.
> Maybe the eMMC signal quality is on the edge on the board. This may
> explain the variability we see in term of stability, but this is just a
> guess. Lowering the max_frequency to 100Mhz seems to do trick for those
> affected by the issue
>
> Worse, the commit created new issues (CRC errors and hangs) on other
> boards, such as the kvim 1 and 2, the p200 or the libretech-cc.
>
> According to amlogic, the Tx phase should not be tuned and left in its
> default configuration, so it is best to just revert the commit.
>
> Signed-off-by: Jerome Brunet <jbrunet@...libre.com>

Thanks, applied for fixes and added a stable/fixes tag.

Kind regards
Uffe

> ---
>  drivers/mmc/host/meson-gx-mmc.c | 19 +------------------
>  1 file changed, 1 insertion(+), 18 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 22438ebfe4e6..4f972b879fe6 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -717,22 +717,6 @@ static int meson_mmc_clk_phase_tuning(struct mmc_host *mmc, u32 opcode,
>  static int meson_mmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
>  {
>         struct meson_host *host = mmc_priv(mmc);
> -       int ret;
> -
> -       /*
> -        * If this is the initial tuning, try to get a sane Rx starting
> -        * phase before doing the actual tuning.
> -        */
> -       if (!mmc->doing_retune) {
> -               ret = meson_mmc_clk_phase_tuning(mmc, opcode, host->rx_clk);
> -
> -               if (ret)
> -                       return ret;
> -       }
> -
> -       ret = meson_mmc_clk_phase_tuning(mmc, opcode, host->tx_clk);
> -       if (ret)
> -               return ret;
>
>         return meson_mmc_clk_phase_tuning(mmc, opcode, host->rx_clk);
>  }
> @@ -763,9 +747,8 @@ static void meson_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>                 if (!IS_ERR(mmc->supply.vmmc))
>                         mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, ios->vdd);
>
> -               /* Reset phases */
> +               /* Reset rx phase */
>                 clk_set_phase(host->rx_clk, 0);
> -               clk_set_phase(host->tx_clk, 270);
>
>                 break;
>
> --
> 2.14.3
>