linux-kernel - Re: [PATCH] mmc: sdhci-msm: Add set_uhs

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Message-ID: <CAPDyKFrRXKbrJyjhKKBuw17_v3kf2YCEHXfMd1-2bOQz6sDgvQ@mail.gmail.com>
Date:	Sat, 23 Jul 2016 11:38:35 +0200
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Georgi Djakov <georgi.djakov@...aro.org>
Cc:	Adrian Hunter <adrian.hunter@...el.com>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	Harjani Ritesh <riteshh@...eaurora.org>,
	Bjorn Andersson <bjorn.andersson@...aro.org>,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: Re: [PATCH] mmc: sdhci-msm: Add set_uhs_signaling() implementation

On 19 July 2016 at 16:52, Georgi Djakov <georgi.djakov@...aro.org> wrote:
> From: Ritesh Harjani <riteshh@...eaurora.org>
>
> To allow UHS mode to work properly, we need to implement a Qualcomm
> specific set_uhs_signaling() callback function. This function differs
> from the sdhci_set_uhs_signaling() in that we need check the clock
> rate and enable UHS timing only if the frequency is above 100MHz.
>
> Signed-off-by: Ritesh Harjani <riteshh@...eaurora.org>
> Signed-off-by: Georgi Djakov <georgi.djakov@...aro.org>

Thanks, applied for next! Updated the change log according to comments
from Adrian.

Kind regards
Uffe

> ---
>
> This patch resolves the mmc_select_hs200 timeouts noticed after merging
> commit a5c1f3e55c99 ("mmc: mmc: do not use CMD13 to get status after
> speed mode switch")
>
> mmc0: mmc_select_hs200 failed, error -110
> mmc0: error -110 whilst initialising MMC card
> mmc0: Reset 0x1 never completed.
> sdhci: =========== REGISTER DUMP (mmc0)===========
> sdhci: Sys addr: 0x00000000 | Version: 0x00002e02
> sdhci: Blk size: 0x00004000 | Blk cnt: 0x00000000
> sdhci: Argument: 0x00000000 | Trn mode: 0x00000000
> sdhci: Present: 0x01f80000 | Host ctl: 0x00000000
> sdhci: Power: 0x00000000 | Blk gap: 0x00000000
> sdhci: Wake-up: 0x00000000 | Clock: 0x00000003
> sdhci: Timeout: 0x00000000 | Int stat: 0x00000000
> sdhci: Int enab: 0x00000000 | Sig enab: 0x00000000
> sdhci: AC12 err: 0x00000000 | Slot int: 0x00000000
> sdhci: Caps: 0x322dc8b2 | Caps_1: 0x00008007
> sdhci: Cmd: 0x00000000 | Max curr: 0x00000000
> sdhci: Host ctl2: 0x00000000
> sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x0000000000000000
> sdhci: ===========================================
>
>  drivers/mmc/host/sdhci-msm.c |   48 +++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 47 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 343e4bd4dc08..d1fce941cdd4 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -410,6 +410,52 @@ retry:
>         return rc;
>  }
>
> +static void sdhci_msm_set_uhs_signaling(struct sdhci_host *host,
> +                                       unsigned int uhs)
> +{
> +       struct mmc_host *mmc = host->mmc;
> +       u16 ctrl_2;
> +
> +       ctrl_2 = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +       /* Select Bus Speed Mode for host */
> +       ctrl_2 &= ~SDHCI_CTRL_UHS_MASK;
> +       switch (uhs) {
> +       case MMC_TIMING_UHS_SDR12:
> +               ctrl_2 |= SDHCI_CTRL_UHS_SDR12;
> +               break;
> +       case MMC_TIMING_UHS_SDR25:
> +               ctrl_2 |= SDHCI_CTRL_UHS_SDR25;
> +               break;
> +       case MMC_TIMING_UHS_SDR50:
> +               ctrl_2 |= SDHCI_CTRL_UHS_SDR50;
> +               break;
> +       case MMC_TIMING_MMC_HS200:
> +       case MMC_TIMING_UHS_SDR104:
> +               ctrl_2 |= SDHCI_CTRL_UHS_SDR104;
> +               break;
> +       case MMC_TIMING_UHS_DDR50:
> +       case MMC_TIMING_MMC_DDR52:
> +               ctrl_2 |= SDHCI_CTRL_UHS_DDR50;
> +               break;
> +       }
> +
> +       /*
> +        * When clock frequency is less than 100MHz, the feedback clock must be
> +        * provided and DLL must not be used so that tuning can be skipped. To
> +        * provide feedback clock, the mode selection can be any value less
> +        * than 3'b011 in bits [2:0] of HOST CONTROL2 register.
> +        */
> +       if (host->clock <= 100000000 &&
> +           (uhs == MMC_TIMING_MMC_HS400 ||
> +            uhs == MMC_TIMING_MMC_HS200 ||
> +            uhs == MMC_TIMING_UHS_SDR104))
> +               ctrl_2 &= ~SDHCI_CTRL_UHS_MASK;
> +
> +       dev_dbg(mmc_dev(mmc), "%s: clock=%u uhs=%u ctrl_2=0x%x\n",
> +               mmc_hostname(host->mmc), host->clock, uhs, ctrl_2);
> +       sdhci_writew(host, ctrl_2, SDHCI_HOST_CONTROL2);
> +}
> +
>  static const struct of_device_id sdhci_msm_dt_match[] = {
>         { .compatible = "qcom,sdhci-msm-v4" },
>         {},
> @@ -422,7 +468,7 @@ static const struct sdhci_ops sdhci_msm_ops = {
>         .reset = sdhci_reset,
>         .set_clock = sdhci_set_clock,
>         .set_bus_width = sdhci_set_bus_width,
> -       .set_uhs_signaling = sdhci_set_uhs_signaling,
> +       .set_uhs_signaling = sdhci_msm_set_uhs_signaling,
>  };
>
>  static const struct sdhci_pltfm_data sdhci_msm_pdata = {