linux-kernel - Re: [PATCH v4] mmc: sdhci_am654: Disable HS400 for AM62P SR1.0 and SR1.1

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Message-ID: <CAPDyKFrZ7jLfAQ1N4_nXZndFvtvKeLqhK-9MjuHUoJA073Pdcg@mail.gmail.com>
Date: Wed, 20 Aug 2025 18:11:24 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Judith Mendez <jm@...com>
Cc: Adrian Hunter <adrian.hunter@...el.com>, linux-mmc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Andrew Davis <afd@...com>
Subject: Re: [PATCH v4] mmc: sdhci_am654: Disable HS400 for AM62P SR1.0 and SR1.1

On Tue, 19 Aug 2025 at 17:28, Judith Mendez <jm@...com> wrote:
>
> This adds SDHCI_AM654_QUIRK_DISABLE_HS400 quirk which shall be used
> to disable HS400 support. AM62P SR1.0 and SR1.1 do not support HS400
> due to errata i2458 [0] so disable HS400 for these SoC revisions.
>
> [0] https://www.ti.com/lit/er/sprz574a/sprz574a.pdf
> Signed-off-by: Judith Mendez <jm@...com>
> Reviewed-by: Andrew Davis <afd@...com>
> Acked-by: Adrian Hunter <adrian.hunter@...el.com>

Can we add a fixes tag? And should this be tagged for stable too?

Kind regards
Uffe

> ---
> This patch was separated from [1] since it will be merged to
> different trees anyways.
>
> Links:
> v3: https://lore.kernel.org/linux-mmc/20250818203310.3066985-1-jm@ti.com/
> v2: [1] https://lore.kernel.org/linux-mmc/20250807225138.1228333-1-jm@ti.com
>
> Changes since v3:
> - Add Andrew's and Adrian's tags
> - Fix message to user as per Andrew's and Adrian's suggestion
>   in v3 to a less imperative tone
> - Fix commit message reference indexes
> ---
>  drivers/mmc/host/sdhci_am654.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
> index 8a099508b939..ffc45930c240 100644
> --- a/drivers/mmc/host/sdhci_am654.c
> +++ b/drivers/mmc/host/sdhci_am654.c
> @@ -155,6 +155,7 @@ struct sdhci_am654_data {
>
>  #define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
>  #define SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA BIT(1)
> +#define SDHCI_AM654_QUIRK_DISABLE_HS400 BIT(2)
>  };
>
>  struct window {
> @@ -764,6 +765,7 @@ static int sdhci_am654_init(struct sdhci_host *host)
>  {
>         struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>         struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
> +       struct device *dev = mmc_dev(host->mmc);
>         u32 ctl_cfg_2 = 0;
>         u32 mask;
>         u32 val;
> @@ -819,6 +821,12 @@ static int sdhci_am654_init(struct sdhci_host *host)
>         if (ret)
>                 goto err_cleanup_host;
>
> +       if (sdhci_am654->quirks & SDHCI_AM654_QUIRK_DISABLE_HS400 &&
> +           host->mmc->caps2 & (MMC_CAP2_HS400 | MMC_CAP2_HS400_ES)) {
> +               dev_info(dev, "HS400 mode not supported on this silicon revision, disabling it\n");
> +               host->mmc->caps2 &= ~(MMC_CAP2_HS400 | MMC_CAP2_HS400_ES);
> +       }
> +
>         ret = __sdhci_add_host(host);
>         if (ret)
>                 goto err_cleanup_host;
> @@ -882,6 +890,12 @@ static int sdhci_am654_get_of_property(struct platform_device *pdev,
>         return 0;
>  }
>
> +static const struct soc_device_attribute sdhci_am654_descope_hs400[] = {
> +       { .family = "AM62PX", .revision = "SR1.0" },
> +       { .family = "AM62PX", .revision = "SR1.1" },
> +       { /* sentinel */ }
> +};
> +
>  static const struct of_device_id sdhci_am654_of_match[] = {
>         {
>                 .compatible = "ti,am654-sdhci-5.1",
> @@ -969,6 +983,10 @@ static int sdhci_am654_probe(struct platform_device *pdev)
>         if (ret)
>                 return dev_err_probe(dev, ret, "parsing dt failed\n");
>
> +       soc = soc_device_match(sdhci_am654_descope_hs400);
> +       if (soc)
> +               sdhci_am654->quirks |= SDHCI_AM654_QUIRK_DISABLE_HS400;
> +
>         host->mmc_host_ops.start_signal_voltage_switch = sdhci_am654_start_signal_voltage_switch;
>         host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
>
> --
> 2.49.0
>