On 26.07.2018 14:26, Aapo Vienamo wrote:
> Automatic pad drive strength calibration is performed on a separate pad
> identical to the ones used for driving the actual bus. Power on the
> calibration pad during the calibration procedure and power it off
> afterwards to save power.
>
> Signed-off-by: Aapo Vienamo <[email protected]>
> Reviewed-by: Mikko Perttunen <[email protected]>
> ---
> drivers/mmc/host/sdhci-tegra.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index 51eda20..363490e 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -53,6 +53,7 @@
> #define SDHCI_TEGRA_SDMEM_COMP_PADCTRL 0x1e0
> #define SDHCI_TEGRA_SDMEM_COMP_PADCTRL_VREF_SEL_MASK 0x0000000f
> #define SDHCI_TEGRA_SDMEM_COMP_PADCTRL_VREF_SEL_VAL 0x7
> +#define SDHCI_TEGRA_SDMEM_COMP_PADCTRL_E_INPUT_E_PWRD BIT(31)
>
> #define SDHCI_TEGRA_AUTO_CAL_STATUS 0x1ec
> #define SDHCI_TEGRA_AUTO_CAL_ACTIVE BIT(31)
> @@ -241,11 +242,30 @@ static void tegra_sdhci_reset(struct sdhci_host
> *host, u8 mask)
> tegra_host->ddr_signaling = false;
> }
>
> +static void tegra_sdhci_configure_cal_pad(struct sdhci_host *host, bool
> enable)
> +{
> + u32 reg;
> +
> + /*
> + * Enable or disable the additional I/O pad used by the drive strength
> + * calibration process.
> + */
> + reg = sdhci_readl(host, SDHCI_TEGRA_SDMEM_COMP_PADCTRL);
> + if (enable)
> + reg |= SDHCI_TEGRA_SDMEM_COMP_PADCTRL_E_INPUT_E_PWRD;
> + else
> + reg &= ~SDHCI_TEGRA_SDMEM_COMP_PADCTRL_E_INPUT_E_PWRD;
> + sdhci_writel(host, reg, SDHCI_TEGRA_SDMEM_COMP_PADCTRL);
> + udelay(1);
Is this necessary on enable and disable?
If it only necessary on enable, I suggest to move it after the call to:
tegra_sdhci_configure_cal_pad(host, true);
--
Stefan
> +}
> +
> static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)
> {
> u32 reg;
> int ret;
>
> + tegra_sdhci_configure_cal_pad(host, true);
> +
> reg = sdhci_readl(host, SDHCI_TEGRA_AUTO_CAL_CONFIG);
> reg |= SDHCI_AUTO_CAL_ENABLE | SDHCI_AUTO_CAL_START;
> sdhci_writel(host, reg, SDHCI_TEGRA_AUTO_CAL_CONFIG);
> @@ -255,6 +275,8 @@ static void tegra_sdhci_pad_autocalib(struct
> sdhci_host *host)
> reg, !(reg & SDHCI_TEGRA_AUTO_CAL_ACTIVE),
> 1, 10000);
>
> + tegra_sdhci_configure_cal_pad(host, false);
> +
> if (ret)
> dev_err(mmc_dev(host->mmc), "Pad autocal timed out\n");
> }
