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SubjectRe: [PATCH 4/8] mmc: tegra: Implement HS400 delay line calibration
On Tue, Aug 07, 2018 at 05:00:00PM +0300, Aapo Vienamo wrote:
> Implement HS400 specific delay line calibration procedure.
>
> Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
> ---
> drivers/mmc/host/sdhci-tegra.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)

Should this be before the previous patch in order to make sure the
calibration is performed as soon as the feature is available. This is
counting beans I guess, but it is technically possible for someone to
get everything up to patch 3/8 and then get the corresponding changes
in the DTS files to enable the mode and then have HS400 enabled without
this calibration.

Thierry

>
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index d81143b..d0b68b7 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -56,6 +56,12 @@
> #define SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300 0x20
> #define SDHCI_MISC_CTRL_ENABLE_DDR50 0x200
>
> +#define SDHCI_TEGRA_VENDOR_DLLCAL_CFG 0x1b0
> +#define SDHCI_TEGRA_DLLCAL_CALIBRATE BIT(31)
> +
> +#define SDHCI_TEGRA_VENDOR_DLLCAL_STA 0x1bc
> +#define SDHCI_TEGRA_DLLCAL_STA_ACTIVE BIT(31)
> +
> #define SDHCI_VNDR_TUN_CTRL0_0 0x1c0
> #define SDHCI_VNDR_TUN_CTRL0_TUN_HW_TAP 0x20000
>
> @@ -584,6 +590,24 @@ static void tegra_sdhci_set_dqs_trim(struct sdhci_host *host, u8 val)
> sdhci_writel(host, reg, SDHCI_TEGRA_VENDOR_CAP_OVERRIDES);
> }
>
> +static void tegra_sdhci_hs400_dll_cal(struct sdhci_host *host)
> +{
> + u32 reg;
> + int err;
> +
> + reg = sdhci_readl(host, SDHCI_TEGRA_VENDOR_DLLCAL_CFG);
> + reg |= SDHCI_TEGRA_DLLCAL_CALIBRATE;
> + sdhci_writel(host, reg, SDHCI_TEGRA_VENDOR_DLLCAL_CFG);

Is this self-clearing? Or do we need to clear it manually in order for
a subsequent calibration procedure to succeed?

Thierry
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