linux-kernel - Re: [PATCH v2] mmc: sdhci_am654: Add sdhci_am654_start_signal_voltage

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Message-ID: <7d3fb0a8-96a1-48cc-97ce-c25d19ded4e7@intel.com>
Date: Mon, 16 Sep 2024 09:14:33 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Judith Mendez <jm@...com>, Ulf Hansson <ulf.hansson@...aro.org>
Cc: linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mmc: sdhci_am654: Add
 sdhci_am654_start_signal_voltage_switch

On 13/09/24 21:54, Judith Mendez wrote:
> The sdhci_start_signal_voltage_switch function sets
> V1P8_SIGNAL_ENA by default after switching to 1v8 signaling.
> V1P8_SIGNAL_ENA determines whether to launch cmd/data on neg
> edge or pos edge of clock.
> 
> Due to some eMMC and SD failures seen across am62x platform,
> do not set V1P8_SIGNAL_ENA by default, only enable the bit
> for devices that require this bit in order to switch to 1v8
> voltage for uhs modes.
> 
> Signed-off-by: Judith Mendez <jm@...com>

Acked-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
> Changes since v1:
> - Invert quirk logic
> - Simplify sdhci_am654_start_signal_voltage_switch() and call
>   sdhci_start_signal_voltage_switch() when the quirk does not apply
> - Simply logic when detecting when quirk should be applied
> ---
>  drivers/mmc/host/sdhci_am654.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
> index 0aa3c40ea6ed8..9ff07aadb2d91 100644
> --- a/drivers/mmc/host/sdhci_am654.c
> +++ b/drivers/mmc/host/sdhci_am654.c
> @@ -155,6 +155,7 @@ struct sdhci_am654_data {
>  	u32 tuning_loop;
>  
>  #define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
> +#define SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA BIT(1)
>  };
>  
>  struct window {
> @@ -356,6 +357,29 @@ static void sdhci_j721e_4bit_set_clock(struct sdhci_host *host,
>  	sdhci_set_clock(host, clock);
>  }
>  
> +static int sdhci_am654_start_signal_voltage_switch(struct mmc_host *mmc, struct mmc_ios *ios)
> +{
> +	struct sdhci_host *host = mmc_priv(mmc);
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
> +	int ret;
> +
> +	if ((sdhci_am654->quirks & SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA) &&
> +	    ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180) {
> +		if (!IS_ERR(mmc->supply.vqmmc)) {
> +			ret = mmc_regulator_set_vqmmc(mmc, ios);
> +			if (ret < 0) {
> +				pr_err("%s: Switching to 1.8V signalling voltage failed,\n",
> +				       mmc_hostname(mmc));
> +				return -EIO;
> +			}
> +		}
> +		return 0;
> +	}
> +
> +	return sdhci_start_signal_voltage_switch(mmc, ios);
> +}
> +
>  static u8 sdhci_am654_write_power_on(struct sdhci_host *host, u8 val, int reg)
>  {
>  	writeb(val, host->ioaddr + reg);
> @@ -844,6 +868,11 @@ static int sdhci_am654_get_of_property(struct platform_device *pdev,
>  	if (device_property_read_bool(dev, "ti,fails-without-test-cd"))
>  		sdhci_am654->quirks |= SDHCI_AM654_QUIRK_FORCE_CDTEST;
>  
> +	/* Suppress v1p8 ena for eMMC and SD with vqmmc supply */
> +	if (!!of_parse_phandle(dev->of_node, "vmmc-supply", 0) ==
> +	    !!of_parse_phandle(dev->of_node, "vqmmc-supply", 0))
> +		sdhci_am654->quirks |= SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA;
> +
>  	sdhci_get_of_property(pdev);
>  
>  	return 0;
> @@ -940,6 +969,7 @@ static int sdhci_am654_probe(struct platform_device *pdev)
>  		goto err_pltfm_free;
>  	}
>  
> +	host->mmc_host_ops.start_signal_voltage_switch = sdhci_am654_start_signal_voltage_switch;
>  	host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
>  
>  	pm_runtime_get_noresume(dev);
> 
> base-commit: cf6444ba528f043398b112ac36e041a4d8685cb1