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References: <20210908013218.29702-1-wenbin.mei@mediatek.com> <20210908013218.29702-3-wenbin.mei@mediatek.com>
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From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Tue, 14 Sep 2021 10:46:09 +0200
Message-ID: <CAPDyKFqTx3wMm6mMy-wY892Nvu-ukqpRS=TSZxYr7e3TJWgF4A@mail.gmail.com>
Subject: Re: [PATCH v3 2/2] mmc: mediatek: Add HS400 online tuning support
To:     Wenbin Mei <wenbin.mei@mediatek.com>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Chaotian Jing <chaotian.jing@mediatek.com>,
        Avri Altman <avri.altman@wdc.com>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Yue Hu <huyue2@yulong.com>, Bean Huo <beanhuo@micron.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        linux-mmc <linux-mmc@vger.kernel.org>,
        DTML <devicetree@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, 8 Sept 2021 at 03:32, Wenbin Mei <wenbin.mei@mediatek.com> wrote:
>
> Due to the influence of the corner IC and vcore voltage, for the stability
> of HS400 mode, we Add HS400 mode online tuning support for mediatek mmc
> host.

My apologies, but I am not familiar with what 'HS400 online tuning'
is? Can you please elaborate on this?

Is it specific for a Mediatek eMMC controller - or is a common eMMC
feature that is described in the eMMC spec?

>
> Signed-off-by: Wenbin Mei <wenbin.mei@mediatek.com>
> Reviewed-by: Chaotian Jing <chaotian.jing@mediatek.com>
> ---
>  drivers/mmc/core/mmc.c    |   8 +++
>  drivers/mmc/host/mtk-sd.c | 118 +++++++++++++++++++++++++++++++++++++-
>  include/linux/mmc/host.h  |   3 +

Please split this patch into a core patch and a mtk-sd patch.

>  3 files changed, 127 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 838726b68ff3..0aa72acd8612 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1222,6 +1222,14 @@ static int mmc_select_hs400(struct mmc_card *card)
>         mmc_set_timing(host, MMC_TIMING_MMC_HS400);
>         mmc_set_bus_speed(card);
>
> +       if (host->ops->execute_hs400_tuning) {
> +               mmc_retune_disable(host);
> +               err = host->ops->execute_hs400_tuning(host, card);
> +               mmc_retune_enable(host);
> +               if (err)
> +                       goto out_err;
> +       }
> +
>         if (host->ops->hs400_complete)
>                 host->ops->hs400_complete(host);
>
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 4dfc246c5f95..484f5c38bfaf 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -258,6 +258,7 @@
>  #define MSDC_PAD_TUNE_RD_SEL     (0x1 << 13)   /* RW */
>  #define MSDC_PAD_TUNE_CMD_SEL    (0x1 << 21)   /* RW */
>
> +#define PAD_DS_TUNE_DLY_SEL       (0x1 << 0)   /* RW */
>  #define PAD_DS_TUNE_DLY1         (0x1f << 2)   /* RW */
>  #define PAD_DS_TUNE_DLY2         (0x1f << 7)   /* RW */
>  #define PAD_DS_TUNE_DLY3         (0x1f << 12)  /* RW */
> @@ -301,6 +302,11 @@
>  #define PAD_CMD_RD_RXDLY_SEL    (0x1 << 11)     /* RW */
>  #define PAD_CMD_TX_DLY          (0x1f << 12)    /* RW */
>
> +/* EMMC50_PAD_DS_TUNE mask */
> +#define PAD_DS_DLY_SEL         (0x1 << 16)     /* RW */
> +#define PAD_DS_DLY1            (0x1f << 10)    /* RW */
> +#define PAD_DS_DLY3            (0x1f << 0)     /* RW */
> +
>  #define REQ_CMD_EIO  (0x1 << 0)
>  #define REQ_CMD_TMO  (0x1 << 1)
>  #define REQ_DAT_ERR  (0x1 << 2)
> @@ -448,11 +454,13 @@ struct msdc_host {
>         bool vqmmc_enabled;
>         u32 latch_ck;
>         u32 hs400_ds_delay;
> +       u32 hs400_ds_dly3;
>         u32 hs200_cmd_int_delay; /* cmd internal delay for HS200/SDR104 */
>         u32 hs400_cmd_int_delay; /* cmd internal delay for HS400 */
>         bool hs400_cmd_resp_sel_rising;
>                                  /* cmd response sample selection for HS400 */
>         bool hs400_mode;        /* current eMMC will run at hs400 mode */
> +       bool hs400_tuning;      /* hs400 mode online tuning */
>         bool internal_cd;       /* Use internal card-detect logic */
>         bool cqhci;             /* support eMMC hw cmdq */
>         struct msdc_save_para save_para; /* used when gate HCLK */
> @@ -1190,7 +1198,8 @@ static bool msdc_cmd_done(struct msdc_host *host, int events,
>         if (!sbc_error && !(events & MSDC_INT_CMDRDY)) {
>                 if (events & MSDC_INT_CMDTMO ||
>                     (cmd->opcode != MMC_SEND_TUNING_BLOCK &&
> -                    cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200))
> +                    cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200 &&
> +                    !host->hs400_tuning))
>                         /*
>                          * should not clear fifo/interrupt as the tune data
>                          * may have alreay come when cmd19/cmd21 gets response
> @@ -1287,7 +1296,8 @@ static void msdc_cmd_next(struct msdc_host *host,
>         if ((cmd->error &&
>             !(cmd->error == -EILSEQ &&
>               (cmd->opcode == MMC_SEND_TUNING_BLOCK ||
> -              cmd->opcode == MMC_SEND_TUNING_BLOCK_HS200))) ||
> +              cmd->opcode == MMC_SEND_TUNING_BLOCK_HS200 ||
> +              host->hs400_tuning))) ||
>             (mrq->sbc && mrq->sbc->error))
>                 msdc_request_done(host, mrq);
>         else if (cmd == mrq->sbc)
> @@ -2251,6 +2261,106 @@ static int msdc_prepare_hs400_tuning(struct mmc_host *mmc, struct mmc_ios *ios)
>         return 0;
>  }
>
> +static int msdc_send_cxd_data(struct mmc_card *card, struct mmc_host *host)
> +{
> +       struct mmc_request mrq = {};
> +       struct mmc_command cmd = {};
> +       struct mmc_data data = {};
> +       unsigned int len = 512;
> +       struct scatterlist sg;
> +       u8 *ext_csd;
> +
> +       ext_csd = kzalloc(len, GFP_KERNEL);
> +       if (!ext_csd)
> +               return -ENOMEM;
> +
> +       mrq.cmd = &cmd;
> +       mrq.data = &data;
> +
> +       cmd.opcode = MMC_SEND_EXT_CSD;
> +       cmd.arg = 0;
> +       cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
> +
> +       data.blksz = len;
> +       data.blocks = 1;
> +       data.flags = MMC_DATA_READ;
> +       data.sg = &sg;
> +       data.sg_len = 1;
> +
> +       sg_init_one(&sg, ext_csd, len);
> +       mmc_set_data_timeout(&data, card);
> +       mmc_wait_for_req(host, &mrq);
> +
> +       kfree(ext_csd);
> +
> +       if (cmd.error)
> +               return cmd.error;
> +       if (data.error)
> +               return data.error;
> +
> +       return 0;

Why do we need to send a MMC_SEND_EXT_CSD command, exactly?

Why can't mmc_send_tuning() work here too? What does the eMMC spec
state about this?

> +}
> +
> +static int msdc_execute_hs400_tuning(struct mmc_host *mmc, struct mmc_card *card)
> +{
> +       struct msdc_host *host = mmc_priv(mmc);
> +       struct msdc_delay_phase dly1_delay;
> +       u32 val, result_dly1 = 0;
> +       int i, ret;
> +
> +       if (host->top_base) {
> +               sdr_set_bits(host->top_base + EMMC50_PAD_DS_TUNE,
> +                            PAD_DS_DLY_SEL);
> +               if (host->hs400_ds_dly3)
> +                       sdr_set_field(host->top_base + EMMC50_PAD_DS_TUNE,
> +                                     PAD_DS_DLY3, host->hs400_ds_dly3);
> +       } else {
> +               sdr_set_bits(host->base + PAD_DS_TUNE, PAD_DS_TUNE_DLY_SEL);
> +               if (host->hs400_ds_dly3)
> +                       sdr_set_field(host->base + PAD_DS_TUNE,
> +                                     PAD_DS_TUNE_DLY3, host->hs400_ds_dly3);
> +       }
> +
> +       host->hs400_tuning = true;
> +       for (i = 0; i < PAD_DELAY_MAX; i++) {
> +               if (host->top_base)
> +                       sdr_set_field(host->top_base + EMMC50_PAD_DS_TUNE,
> +                                     PAD_DS_DLY1, i);
> +               else
> +                       sdr_set_field(host->base + PAD_DS_TUNE,
> +                                     PAD_DS_TUNE_DLY1, i);
> +               ret = msdc_send_cxd_data(card, mmc);
> +               if (!ret)
> +                       result_dly1 |= (1 << i);
> +       }
> +       host->hs400_tuning = false;
> +
> +       dly1_delay = get_best_delay(host, result_dly1);
> +       if (dly1_delay.maxlen == 0) {
> +               dev_err(host->dev, "Failed to get DLY1 delay!\n");
> +               goto fail;
> +       }
> +       if (host->top_base)
> +               sdr_set_field(host->top_base + EMMC50_PAD_DS_TUNE,
> +                             PAD_DS_DLY1, dly1_delay.final_phase);
> +       else
> +               sdr_set_field(host->base + PAD_DS_TUNE,
> +                             PAD_DS_TUNE_DLY1, dly1_delay.final_phase);
> +
> +       if (host->top_base)
> +               val = readl(host->top_base + EMMC50_PAD_DS_TUNE);
> +       else
> +               val = readl(host->base + PAD_DS_TUNE);
> +
> +       dev_info(host->dev, "Fianl PAD_DS_TUNE: 0x%x\n", val);
> +
> +       return 0;
> +
> +fail:
> +       dev_err(host->dev, "Failed to tuning DS pin delay!\n");
> +       return -EIO;
> +}

[...]

Kind regards
Uffe