On 18 April 2017 at 12:05, Haibo Chen <haibo.chen@xxxxxxx> wrote:
> USDHC tuning circuit should be reset before every time card enumeration
> or re-enumeration.
>
> SD3.0 card need tuning. For SDR104 card, when system suspend in standby
> mode, and then resume back, the IO timing is still SDR104(tuned) which
> may result in card re-enumeration fail in low card speed(400khz) for some
> cards. And we did meet the issue that in certain probability, SDR104
> card meet mmc command CRC/Timeout error when send CMD2 during mmc bus
> resume.
>
> This patch reset the tuning circuit when the ios timing is
> MMC_TIMING_LEGACY/MMC_TIMING_MMC_HS/MMC_TIMING_SD_HS, which means both
> mmc_power_up() and mmc_power_off() will reset the tuning circuit.
>
> Signed-off-by: Haibo Chen <haibo.chen@xxxxxxx>
> ---
> drivers/mmc/host/sdhci-esdhc-imx.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
> index abad67a..23d8b8a 100644
> --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> @@ -889,6 +889,28 @@ static void esdhc_set_strobe_dll(struct sdhci_host *host)
> }
> }
>
> +static void esdhc_reset_tuning(struct sdhci_host *host)
> +{
> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> + struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host);
> + u32 ctrl;
> +
> + /* Rest the tuning circurt */
> + if (esdhc_is_usdhc(imx_data)) {
> + if (imx_data->socdata->flags & ESDHC_FLAG_MAN_TUNING) {
> + ctrl = readl(host->ioaddr + ESDHC_MIX_CTRL);
> + ctrl &= ~ESDHC_MIX_CTRL_SMPCLK_SEL;
> + ctrl &= ~ESDHC_MIX_CTRL_FBCLK_SEL;
> + writel(ctrl, host->ioaddr + ESDHC_MIX_CTRL);
> + writel(0, host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
> + } else if (imx_data->socdata->flags & ESDHC_FLAG_STD_TUNING) {
> + ctrl = readl(host->ioaddr + SDHCI_ACMD12_ERR);
> + ctrl &= ~ESDHC_MIX_CTRL_SMPCLK_SEL;
> + writel(ctrl, host->ioaddr + SDHCI_ACMD12_ERR);
> + }
> + }
> +}
> +
> static void esdhc_set_uhs_signaling(struct sdhci_host *host, unsigned timing)
> {
> u32 m;
> @@ -932,6 +954,10 @@ static void esdhc_set_uhs_signaling(struct sdhci_host *host, unsigned timing)
> host->ops->set_clock(host, host->clock);
> esdhc_set_strobe_dll(host);
> break;
> + case MMC_TIMING_LEGACY:
> + default:
> + esdhc_reset_tuning(host);
> + break;
I understand this fixes the problem.
However a more appropriate fix would be to reset tuning when
->ios.power_mode == MMC_POWER_UP, don't you think?
> }
>
> esdhc_change_pinstate(host, timing);
> --
> 1.9.1
>
Kind regards
Uffe
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