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Subject: Re: [PATCH 2/7] mmc: tegra: Reconfigure pad voltages during voltage
 switching
To:     Aapo Vienamo <avienamo@nvidia.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Mikko Perttunen <mperttunen@nvidia.com>
Cc:     linux-mmc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1532090746-15863-1-git-send-email-avienamo@nvidia.com>
 <1532090746-15863-3-git-send-email-avienamo@nvidia.com>
From:   Mikko Perttunen <cyndis@kapsi.fi>
Message-ID: <45dff1ef-c86e-0265-3386-fe95251b9130@kapsi.fi>
Date:   Wed, 25 Jul 2018 09:41:05 +0300
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On 20.07.2018 15:45, Aapo Vienamo wrote:
> Parse the pinctrl states from the device tree and implement pad voltage
> state reconfiguration in the mmc start_signal_voltage_switch() callback.
> This is done in the mmc callback because the order of pad
> reconfiguration and sdhci voltage switch depend on the voltage to which
> the transition occurs.
> 
> Add NVQUIRK_NEEDS_PAD_CONTROL and add set it for Tegra210 and Tegra186.
> 
> Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
> ---
>   drivers/mmc/host/sdhci-tegra.c | 91 +++++++++++++++++++++++++++++++++++++++---
>   1 file changed, 85 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index ddf00166..f108c48 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -21,6 +21,7 @@
>   #include <linux/io.h>
>   #include <linux/of.h>
>   #include <linux/of_device.h>
> +#include <linux/pinctrl/consumer.h>
>   #include <linux/reset.h>
>   #include <linux/mmc/card.h>
>   #include <linux/mmc/host.h>
> @@ -55,6 +56,7 @@
>   #define NVQUIRK_ENABLE_SDR104		BIT(4)
>   #define NVQUIRK_ENABLE_DDR50		BIT(5)
>   #define NVQUIRK_HAS_PADCALIB		BIT(6)
> +#define NVQUIRK_NEEDS_PAD_CONTROL	BIT(7)
>   
>   struct sdhci_tegra_soc_data {
>   	const struct sdhci_pltfm_data *pdata;
> @@ -66,8 +68,12 @@ struct sdhci_tegra {
>   	struct gpio_desc *power_gpio;
>   	bool ddr_signaling;
>   	bool pad_calib_required;
> +	bool pad_control_required;
>   
>   	struct reset_control *rst;
> +	struct pinctrl *pinctrl_sdmmc;
> +	struct pinctrl_state *pinctrl_state_3v3;
> +	struct pinctrl_state *pinctrl_state_1v8;
>   };
>   
>   static u16 tegra_sdhci_readw(struct sdhci_host *host, int reg)
> @@ -286,14 +292,80 @@ static int tegra_sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)
>   	return mmc_send_tuning(host->mmc, opcode, NULL);
>   }
>   
> -static void tegra_sdhci_voltage_switch(struct sdhci_host *host)
> +static int tegra_sdhci_set_padctrl(struct sdhci_host *host, int voltage)
>   {
>   	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>   	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
> -	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
> +	int ret;
> +
> +	if (!tegra_host->pad_control_required)
> +		return 0;
> +
> +	if (voltage == MMC_SIGNAL_VOLTAGE_180) {
> +		ret = pinctrl_select_state(tegra_host->pinctrl_sdmmc,
> +					   tegra_host->pinctrl_state_1v8);
> +		if (ret < 0)
> +			dev_err(mmc_dev(host->mmc),
> +				"setting 1.8V failed, ret: %d\n", ret);
> +	} else {
> +		ret = pinctrl_select_state(tegra_host->pinctrl_sdmmc,
> +					   tegra_host->pinctrl_state_3v3);
> +		if (ret < 0)
> +			dev_err(mmc_dev(host->mmc),
> +				"setting 3.3V failed, ret: %d\n", ret);
> +	}
>   
> -	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
> -		tegra_host->pad_calib_required = true;
> +	return ret;
> +}
> +
> +static int sdhci_tegra_start_signal_voltage_switch(struct mmc_host *mmc,
> +						   struct mmc_ios *ios)
> +{
> +	struct sdhci_host *host = mmc_priv(mmc);
> +	int ret = 0;
> +
> +	if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330) {
> +		ret = tegra_sdhci_set_padctrl(host, ios->signal_voltage);
> +		if (ret < 0)
> +			return ret;
> +		ret = sdhci_start_signal_voltage_switch(mmc, ios);
> +	} else if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180) {
> +		ret = sdhci_start_signal_voltage_switch(mmc, ios);
> +		if (ret < 0)
> +			return ret;
> +		ret = tegra_sdhci_set_padctrl(host, ios->signal_voltage);
> +	}
> +
> +	return ret;
> +}
> +
> +static void tegra_sdhci_init_pinctrl_info(struct device *dev,
> +					  struct sdhci_tegra *tegra_host)
> +{
> +	tegra_host->pinctrl_sdmmc = devm_pinctrl_get(dev);
> +	if (IS_ERR_OR_NULL(tegra_host->pinctrl_sdmmc)) {

Can this ever return NULL, considering ARCH_TEGRA selects PINCTRL? 
IS_ERR is probably better. Same for the two other checks in this function.

> +		dev_dbg(dev, "No pinctrl info, err: %ld\n",
> +			PTR_ERR(tegra_host->pinctrl_sdmmc));
> +		return;
> +	}
> +
> +	tegra_host->pinctrl_state_3v3 =
> +		pinctrl_lookup_state(tegra_host->pinctrl_sdmmc, "sdmmc-3v3");
> +	if (IS_ERR_OR_NULL(tegra_host->pinctrl_state_3v3)) {
> +		dev_err(dev, "Missing 3.3V pad state, err: %ld\n",
> +			PTR_ERR(tegra_host->pinctrl_state_3v3));
> +		return;
> +	}
> +
> +	tegra_host->pinctrl_state_1v8 =
> +		pinctrl_lookup_state(tegra_host->pinctrl_sdmmc, "sdmmc-1v8");
> +	if (IS_ERR_OR_NULL(tegra_host->pinctrl_state_1v8)) {
> +		dev_err(dev, "Missing 1.8V pad state, err: %ld\n",
> +			  PTR_ERR(tegra_host->pinctrl_state_3v3));
> +		return;
> +	}
> +
> +	tegra_host->pad_control_required = true; >   }
>   
>   static const struct sdhci_ops tegra_sdhci_ops = {
> @@ -305,7 +377,6 @@ static const struct sdhci_ops tegra_sdhci_ops = {
>   	.reset      = tegra_sdhci_reset,
>   	.platform_execute_tuning = tegra_sdhci_execute_tuning,
>   	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
> -	.voltage_switch = tegra_sdhci_voltage_switch,
>   	.get_max_clock = tegra_sdhci_get_max_clock,
>   };
>   
> @@ -362,7 +433,6 @@ static const struct sdhci_ops tegra114_sdhci_ops = {
>   	.reset      = tegra_sdhci_reset,
>   	.platform_execute_tuning = tegra_sdhci_execute_tuning,
>   	.set_uhs_signaling = tegra_sdhci_set_uhs_signaling,
> -	.voltage_switch = tegra_sdhci_voltage_switch,
>   	.get_max_clock = tegra_sdhci_get_max_clock,
>   };
>   
> @@ -419,6 +489,7 @@ static const struct sdhci_pltfm_data sdhci_tegra210_pdata = {
>   
>   static const struct sdhci_tegra_soc_data soc_data_tegra210 = {
>   	.pdata = &sdhci_tegra210_pdata,
> +	.nvquirks = NVQUIRK_NEEDS_PAD_CONTROL,
>   };
>   
>   static const struct sdhci_pltfm_data sdhci_tegra186_pdata = {
> @@ -442,6 +513,7 @@ static const struct sdhci_pltfm_data sdhci_tegra186_pdata = {
>   
>   static const struct sdhci_tegra_soc_data soc_data_tegra186 = {
>   	.pdata = &sdhci_tegra186_pdata,
> +	.nvquirks = NVQUIRK_NEEDS_PAD_CONTROL,
>   };
>   
>   static const struct of_device_id sdhci_tegra_dt_match[] = {
> @@ -478,8 +550,15 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
>   	tegra_host = sdhci_pltfm_priv(pltfm_host);
>   	tegra_host->ddr_signaling = false;
>   	tegra_host->pad_calib_required = false;
> +	tegra_host->pad_control_required = false;
>   	tegra_host->soc_data = soc_data;
>   
> +	if (soc_data->nvquirks & NVQUIRK_NEEDS_PAD_CONTROL) {
> +		host->mmc_host_ops.start_signal_voltage_switch =
> +			sdhci_tegra_start_signal_voltage_switch;
> +		tegra_sdhci_init_pinctrl_info(&pdev->dev, tegra_host);
> +	}
> +

Do we know here if the controller is for eMMC or SD? If it's for SD we 
should probably print a warning if the pinctrl info is not available. 
Later we would also need to disable 1.8V modes if we fail to get the 
pinctrl info.

Cheers,
Mikko

>   	rc = mmc_of_parse(host->mmc);
>   	if (rc)
>   		goto err_parse_dt;
>