linux-kernel - Re: [PATCH] mmc: meson-mx-sdhc: Fix initialization frozen issue

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Message-ID: <CAPDyKFqyi97kjdiNM60WYK+cs4pw5pW3AyfiWKnsCRXd5BXUww@mail.gmail.com>
Date:   Thu, 14 Sep 2023 16:45:53 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Ziyang Huang <hzyitc@...look.com>,
        martin.blumenstingl@...glemail.com,
        Thorsten Leemhuis <regressions@...mhuis.info>
Cc:     neil.armstrong@...aro.org, khilman@...libre.com,
        jbrunet@...libre.com, linux-mmc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: meson-mx-sdhc: Fix initialization frozen issue

+ Thorsten

On Mon, 19 Jun 2023 at 19:36, Ziyang Huang <hzyitc@...look.com> wrote:
>
> Commit 4bc31edebde5 ("mmc: core: Set HS clock speed before sending
> HS CMD13") set HS clock (52MHz) before switching to HS mode. For this
> freq, FCLK_DIV5 will be selected and div value is 10 (reg value is 9).
> Then we set rx_clk_phase to 11 or 15 which is out of range and make
> hardware frozen. After we send command request, no irq will be
> interrupted and the mmc driver will keep to wait for request finished,
> even durning rebooting.
>
> So let's set a common value - 1 just for initialization. Then let
> meson_mx_sdhc_execute_tuning() to find the accurate value for data
> transfer.
>
> Fixes: e4bf1b0970ef ("mmc: host: meson-mx-sdhc: new driver for the Amlogic Meson SDHC host")
> Signed-off-by: Ziyang Huang <hzyitc@...look.com>

I don't quite understand if this patch is ok for everybody for me to apply?

It seems like it solves at least some part of the problems that
Martin/Thorsten were looking at too [1], right?

Kind regards
Uffe

[1]
https://lore.kernel.org/all/CAFBinCD0RT0p-jk86W0JuMT3ufohRh1RqWCcM35DKZJpuc10HQ@mail.gmail.com/#r

> ---
>  drivers/mmc/host/meson-mx-sdhc-mmc.c | 26 +++-----------------------
>  1 file changed, 3 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-mx-sdhc-mmc.c b/drivers/mmc/host/meson-mx-sdhc-mmc.c
> index da85c2f2..a01090a2 100644
> --- a/drivers/mmc/host/meson-mx-sdhc-mmc.c
> +++ b/drivers/mmc/host/meson-mx-sdhc-mmc.c
> @@ -269,7 +269,6 @@ static int meson_mx_sdhc_enable_clks(struct mmc_host *mmc)
>  static int meson_mx_sdhc_set_clk(struct mmc_host *mmc, struct mmc_ios *ios)
>  {
>         struct meson_mx_sdhc_host *host = mmc_priv(mmc);
> -       u32 rx_clk_phase;
>         int ret;
>
>         meson_mx_sdhc_disable_clks(mmc);
> @@ -290,31 +289,12 @@ static int meson_mx_sdhc_set_clk(struct mmc_host *mmc, struct mmc_ios *ios)
>                 mmc->actual_clock = clk_get_rate(host->sd_clk);
>
>                 /*
> -                * according to Amlogic the following latching points are
> -                * selected with empirical values, there is no (known) formula
> -                * to calculate these.
> +                * This value is just for initialization. For data transmission,
> +                * meson_mx_sdhc_execute_tuning() will find a accurate value
>                  */
> -               if (mmc->actual_clock > 100000000) {
> -                       rx_clk_phase = 1;
> -               } else if (mmc->actual_clock > 45000000) {
> -                       if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330)
> -                               rx_clk_phase = 15;
> -                       else
> -                               rx_clk_phase = 11;
> -               } else if (mmc->actual_clock >= 25000000) {
> -                       rx_clk_phase = 15;
> -               } else if (mmc->actual_clock > 5000000) {
> -                       rx_clk_phase = 23;
> -               } else if (mmc->actual_clock > 1000000) {
> -                       rx_clk_phase = 55;
> -               } else {
> -                       rx_clk_phase = 1061;
> -               }
> -
>                 regmap_update_bits(host->regmap, MESON_SDHC_CLK2,
>                                    MESON_SDHC_CLK2_RX_CLK_PHASE,
> -                                  FIELD_PREP(MESON_SDHC_CLK2_RX_CLK_PHASE,
> -                                             rx_clk_phase));
> +                                  FIELD_PREP(MESON_SDHC_CLK2_RX_CLK_PHASE, 1));
>         } else {
>                 mmc->actual_clock = 0;
>         }
> --
> 2.34.1
>