On 26/12/16 11:46, Yangbo Lu wrote:
> The eSDHC_PRSSTAT[SDSTB] bit indicates whether the internal card clock is
> stable. This bit is for the host driver to poll clock status when changing
> the clock frequency. It is recommended to clear eSDHC_SYSCTL[SDCLKEN]
> to remove glitch on the card clock when the frequency is changing. This
> patch is to disable SDCLKEN bit before changing frequency and enable it
> after SDSTB bit is set.
>
> Signed-off-by: Yangbo Lu <yangbo.lu@xxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
> Changes for v2:
> - added Adrian into to list
> ---
> drivers/mmc/host/sdhci-esdhc.h | 5 +++++
> drivers/mmc/host/sdhci-of-esdhc.c | 21 ++++++++++++++++++---
> 2 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-esdhc.h b/drivers/mmc/host/sdhci-esdhc.h
> index 8cd8449..ece8b37 100644
> --- a/drivers/mmc/host/sdhci-esdhc.h
> +++ b/drivers/mmc/host/sdhci-esdhc.h
> @@ -31,6 +31,10 @@
> * eSDHC register definition
> */
>
> +/* Present State Register */
> +#define ESDHC_PRSSTAT 0x24
> +#define ESDHC_CLOCK_STABLE 0x00000008
> +
> /* Protocol Control Register */
> #define ESDHC_PROCTL 0x28
> #define ESDHC_CTRL_4BITBUS (0x1 << 1)
> @@ -43,6 +47,7 @@
> #define ESDHC_CLOCK_MASK 0x0000fff0
> #define ESDHC_PREDIV_SHIFT 8
> #define ESDHC_DIVIDER_SHIFT 4
> +#define ESDHC_CLOCK_SDCLKEN 0x00000008
> #define ESDHC_CLOCK_PEREN 0x00000004
> #define ESDHC_CLOCK_HCKEN 0x00000002
> #define ESDHC_CLOCK_IPGEN 0x00000001
> diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c
> index 9a6eb44..0849885 100644
> --- a/drivers/mmc/host/sdhci-of-esdhc.c
> +++ b/drivers/mmc/host/sdhci-of-esdhc.c
> @@ -431,6 +431,7 @@ static void esdhc_of_set_clock(struct sdhci_host *host, unsigned int clock)
> struct sdhci_esdhc *esdhc = sdhci_pltfm_priv(pltfm_host);
> int pre_div = 1;
> int div = 1;
> + u32 timeout;
> u32 temp;
>
> host->mmc->actual_clock = 0;
> @@ -451,8 +452,8 @@ static void esdhc_of_set_clock(struct sdhci_host *host, unsigned int clock)
> }
>
> temp = sdhci_readl(host, ESDHC_SYSTEM_CONTROL);
> - temp &= ~(ESDHC_CLOCK_IPGEN | ESDHC_CLOCK_HCKEN | ESDHC_CLOCK_PEREN
> - | ESDHC_CLOCK_MASK);
> + temp &= ~(ESDHC_CLOCK_SDCLKEN | ESDHC_CLOCK_IPGEN | ESDHC_CLOCK_HCKEN |
> + ESDHC_CLOCK_PEREN | ESDHC_CLOCK_MASK);
> sdhci_writel(host, temp, ESDHC_SYSTEM_CONTROL);
>
> while (host->max_clk / pre_div / 16 > clock && pre_div < 256)
> @@ -472,7 +473,21 @@ static void esdhc_of_set_clock(struct sdhci_host *host, unsigned int clock)
> | (div << ESDHC_DIVIDER_SHIFT)
> | (pre_div << ESDHC_PREDIV_SHIFT));
> sdhci_writel(host, temp, ESDHC_SYSTEM_CONTROL);
> - mdelay(1);
> +
> + /* Wait max 20 ms */
> + timeout = 20;
> + while (!(sdhci_readl(host, ESDHC_PRSSTAT) & ESDHC_CLOCK_STABLE)) {
> + if (timeout == 0) {
> + pr_err("%s: Internal clock never stabilised.\n",
> + mmc_hostname(host->mmc));
> + return;
> + }
> + timeout--;
> + mdelay(1);
> + }
> +
> + temp |= ESDHC_CLOCK_SDCLKEN;
> + sdhci_writel(host, temp, ESDHC_SYSTEM_CONTROL);
> }
>
> static void esdhc_pltfm_set_bus_width(struct sdhci_host *host, int width)
>
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