linux-kernel - Re: [PATCH v3] mmc: sdhci_am654: Disable HS400 for AM62P SR1.0 and SR1.1

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Message-ID: <f07d0353-4103-4776-a303-f6a3aad5bf15@ti.com>
Date: Mon, 18 Aug 2025 15:38:41 -0500
From: Andrew Davis <afd@...com>
To: Judith Mendez <jm@...com>, Adrian Hunter <adrian.hunter@...el.com>,
        Ulf
 Hansson <ulf.hansson@...aro.org>
CC: <linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] mmc: sdhci_am654: Disable HS400 for AM62P SR1.0 and
 SR1.1

On 8/18/25 3:33 PM, Judith Mendez 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>
> ---
> This patch was separated from [0] since it will be merged to
> different trees anyways.
> 
> Link to v2:
> [0] https://lore.kernel.org/linux-mmc/20250807225138.1228333-1-jm@ti.com
> ---
>   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..cc8c4145bf2b 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, "Disable descoped HS400 mode for this silicon revision\n");

Messages to the user do not need to be imperative, maybe:

"Disabling HS400 mode not supported on this silicon revision\n"

Not a blocker,

Reviewed-by: Andrew Davis <afd@...com>

> +		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;
>