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SubjectRe: [PATCH 03/10] mmc: tegra: Power on the calibration pad
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Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>

On 24.07.2018 17:34, 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 <avienamo@nvidia.com>
> ---
> drivers/mmc/host/sdhci-tegra.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index 6008e2f..61067b7 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -209,11 +209,30 @@ 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_PAD_E_INPUT_OR_E_PWRD;
> + else
> + reg &= ~SDHCI_TEGRA_PAD_E_INPUT_OR_E_PWRD;
> + sdhci_writel(host, reg, SDHCI_TEGRA_SDMEM_COMP_PADCTRL);
> + udelay(1);
> +}
> +
> static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)
> {
> unsigned timeout = 10;
> u32 reg;
>
> + 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);
> @@ -227,6 +246,8 @@ static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)
> timeout--;
> } while (timeout);
>
> + tegra_sdhci_configure_cal_pad(host, false);
> +
> if (timeout == 0)
> dev_err(mmc_dev(host->mmc), "Pad autocal timed out\n");
> }
>

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