linux-kernel - Re: [PATCH v2] mmc: meson-mx-sdhc: Fix initialization frozen issue

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Date:   Fri, 3 Nov 2023 12:15:54 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Ziyang Huang <hzyitc@...look.com>
Cc:     neil.armstrong@...aro.org, khilman@...libre.com,
        jbrunet@...libre.com, martin.blumenstingl@...glemail.com,
        yinxin_1989@...yun.com, regressions@...mhuis.info,
        briannorris@...omium.org, linux-mmc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anand Moon <linux.amoon@...il.com>
Subject: Re: [PATCH v2] mmc: meson-mx-sdhc: Fix initialization frozen issue

+ Anand

On Tue, 10 Oct 2023 at 18:44, 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 it to Phase 90 which should work in most cases. Then let
> meson_mx_sdhc_execute_tuning() to find the accurate value for data
> transfer.
>
> If this doesn't work, maybe need to define a factor in dts.
>
> Fixes: e4bf1b0970ef ("mmc: host: meson-mx-sdhc: new driver for the Amlogic Meson SDHC host")
> Signed-off-by: Ziyang Huang <hzyitc@...look.com>

Let's give this a try! Although, rather than queuing it as a fix for
v6.7, I am picking it for v6.8 and adding a stable tag, this should
allow it to become a bit more tested first.

Kind regards
Uffe


> ---
> Changes since v1:
>   Use Phase 90 instand of value 1
>
>  drivers/mmc/host/meson-mx-sdhc-mmc.c | 26 +++++---------------------
>  1 file changed, 5 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-mx-sdhc-mmc.c b/drivers/mmc/host/meson-mx-sdhc-mmc.c
> index 97168cdfa8e9..29698fceb89c 100644
> --- a/drivers/mmc/host/meson-mx-sdhc-mmc.c
> +++ b/drivers/mmc/host/meson-mx-sdhc-mmc.c
> @@ -269,7 +269,7 @@ 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;
> +       u32 val, rx_clk_phase;
>         int ret;
>
>         meson_mx_sdhc_disable_clks(mmc);
> @@ -290,27 +290,11 @@ 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.
> +                * Phase 90 should work in most cases. 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_read(host->regmap, MESON_SDHC_CLKC, &val);
> +               rx_clk_phase = FIELD_GET(MESON_SDHC_CLKC_CLK_DIV, val) / 4;
>                 regmap_update_bits(host->regmap, MESON_SDHC_CLK2,
>                                    MESON_SDHC_CLK2_RX_CLK_PHASE,
>                                    FIELD_PREP(MESON_SDHC_CLK2_RX_CLK_PHASE,
> --
> 2.34.1
>