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Subject: Re: [PATCH V4 5/7] mmc: sdhci: add Auto CMD Auto Select support
To:     Chunyan Zhang <zhang.lyra@gmail.com>
Cc:     Chunyan Zhang <zhang.chunyan@linaro.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        linux-mmc@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Orson Zhai <orsonzhai@gmail.com>,
        Baolin Wang <baolin.wang@linaro.org>,
        Billows Wu <billows.wu@spreadtrum.com>,
        Jason Wu <jason.wu@unisoc.com>
References: <1532340508-8749-1-git-send-email-zhang.chunyan@linaro.org>
 <1532340508-8749-6-git-send-email-zhang.chunyan@linaro.org>
 <33ceb61c-3e09-c336-e9b9-87c01336f56c@intel.com>
 <CAAfSe-vVEve63y-Pc0QF6w7vc37cbbbOknGkp9SmocXyNX3J4g@mail.gmail.com>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
 Business Identity Code: 0357606 - 4, Domiciled in Helsinki
Message-ID: <f810df5a-2cc4-a534-9fdc-2575ae81cf4b@intel.com>
Date:   Tue, 31 Jul 2018 11:05:35 +0300
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On 31/07/18 10:04, Chunyan Zhang wrote:
> Hi Adrian,
> 
> On 30 July 2018 at 21:06, Adrian Hunter <adrian.hunter@intel.com> wrote:
>> On 23/07/18 13:08, Chunyan Zhang wrote:
>>> As SD Host Controller Specification v4.10 documents:
>>> Host Controller Version 4.10 defines this "Auto CMD Auto Select" mode.
>>> Selection of Auto CMD depends on setting of CMD23 Enable in the Host
>>> Control 2 register which indicates whether card supports CMD23. If CMD23
>>> Enable =1, Auto CMD23 is used and if CMD23 Enable =0, Auto CMD12 is
>>> used. In case of Version 4.10 or later, use of Auto CMD Auto Select is
>>> recommended rather than use of Auto CMD12 Enable or Auto CMD23
>>> Enable.
>>>
>>> This patch add this new mode support.
>>>
>>> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
>>> ---
>>>  drivers/mmc/host/sdhci.c | 61 +++++++++++++++++++++++++++++++++++++++---------
>>>  drivers/mmc/host/sdhci.h |  2 ++
>>>  2 files changed, 52 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>> index 5acea3d..5c60590 100644
>>> --- a/drivers/mmc/host/sdhci.c
>>> +++ b/drivers/mmc/host/sdhci.c
>>> @@ -311,6 +311,23 @@ static void sdhci_config_dma(struct sdhci_host *host)
>>>       sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
>>>  }
>>>
>>> +static void sdhci_enable_cmd23(struct sdhci_host *host)
>>> +{
>>> +     u16 ctrl2;
>>> +
>>> +     /*
>>> +      * This is used along with "Auto CMD Auto Select" feature,
>>> +      * which is introduced from v4.10, if card supports CMD23,
>>> +      * Auto CMD23 should be used instead of Auto CMD12.
>>> +      */
>>> +     if (host->version >= SDHCI_SPEC_410 &&
>>> +         (host->mmc->caps & MMC_CAP_CMD23)) {
>>
>> That is the host capability.  It needs to be the card capability.
> 
> Could you please elaborate the issue?
> 
> I thought we're setting for host here.  Do you mean we need to see the
> card capability?

Yes. SDHCI_TRNS_AUTO_SEL selects auto-CMD23 or auto-CMD12 based on this
setting, so this must reflect the card's capability.

> 
>>
>>> +             ctrl2 = sdhci_readw(host, SDHCI_HOST_CONTROL2);
>>> +             ctrl2 |= SDHCI_CMD23_ENABLE;
>>> +             sdhci_writew(host, ctrl2, SDHCI_HOST_CONTROL2);
>>> +     }
>>> +}
>>> +
>>>  static void sdhci_init(struct sdhci_host *host, int soft)
>>>  {
>>>       struct mmc_host *mmc = host->mmc;
>>> @@ -329,6 +346,8 @@ static void sdhci_init(struct sdhci_host *host, int soft)
>>>               host->clock = 0;
>>>               mmc->ops->set_ios(mmc, &mmc->ios);
>>>       }
>>> +
>>> +     sdhci_enable_cmd23(host);
>>>  }
>>>
>>>  static void sdhci_reinit(struct sdhci_host *host)
>>> @@ -1093,6 +1112,36 @@ static inline bool sdhci_auto_cmd12(struct sdhci_host *host,
>>>              !mrq->cap_cmd_during_tfr;
>>>  }
>>>
>>> +static inline void sdhci_auto_cmd_select(struct sdhci_host *host,
>>> +                                      struct mmc_command *cmd,
>>> +                                      u16 *mode)
>>> +{
>>> +     bool use_cmd12 = sdhci_auto_cmd12(host, cmd->mrq) &&
>>> +                      (cmd->opcode != SD_IO_RW_EXTENDED);
>>> +     bool use_cmd23 = cmd->mrq->sbc && (host->flags & SDHCI_AUTO_CMD23);
>>> +
>>> +     /*
>>> +      * In case of Version 4.10 or later, use of 'Auto CMD Auto
>>> +      * Select' is recommended rather than use of 'Auto CMD12
>>> +      * Enable' or 'Auto CMD23 Enable'.
>>> +      */
>>> +     if (host->version >= SDHCI_SPEC_410 && (use_cmd12 || use_cmd23)) {
>>> +             *mode |= SDHCI_TRNS_AUTO_SEL;
>>
>> As noted in patch 4, the CMD23 argument is not just the block count for eMMC.
> 
> Probably I haven't got your point...
> 
>>From what I understand, auto_sel mode doesn't need argument2. Doesn't
> this work for eMMC?

CMD23 always needs an argument

> 
> The test platform I used was just eMMC only, haven't found problem.

Because the bits that are missing from the CMD23 argument (reliable write,
context id, etc) will not make the command fail.

> 
> Thanks,
> Chunyan
> 
>>
>>> +             return;
>>> +     }
>>> +
>>> +     /*
>>> +      * If we are sending CMD23, CMD12 never gets sent
>>> +      * on successful completion (so no Auto-CMD12).
>>> +      */
>>> +     if (use_cmd12) {
>>> +             *mode |= SDHCI_TRNS_AUTO_CMD12;
>>> +     } else if (use_cmd23) {
>>> +             *mode |= SDHCI_TRNS_AUTO_CMD23;
>>> +             sdhci_writel(host, cmd->mrq->sbc->arg, SDHCI_ARGUMENT2);
>>> +     }
>>> +}
>>> +
>>>  static void sdhci_set_transfer_mode(struct sdhci_host *host,
>>>       struct mmc_command *cmd)
>>>  {
>>> @@ -1119,17 +1168,7 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host,
>>>
>>>       if (mmc_op_multi(cmd->opcode) || data->blocks > 1) {
>>>               mode = SDHCI_TRNS_BLK_CNT_EN | SDHCI_TRNS_MULTI;
>>> -             /*
>>> -              * If we are sending CMD23, CMD12 never gets sent
>>> -              * on successful completion (so no Auto-CMD12).
>>> -              */
>>> -             if (sdhci_auto_cmd12(host, cmd->mrq) &&
>>> -                 (cmd->opcode != SD_IO_RW_EXTENDED))
>>> -                     mode |= SDHCI_TRNS_AUTO_CMD12;
>>> -             else if (cmd->mrq->sbc && (host->flags & SDHCI_AUTO_CMD23)) {
>>> -                     mode |= SDHCI_TRNS_AUTO_CMD23;
>>> -                     sdhci_writel(host, cmd->mrq->sbc->arg, SDHCI_ARGUMENT2);
>>> -             }
>>> +             sdhci_auto_cmd_select(host, cmd, &mode);
>>>       }
>>>
>>>       if (data->flags & MMC_DATA_READ)
>>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>>> index 81aae07..a8f4ec2 100644
>>> --- a/drivers/mmc/host/sdhci.h
>>> +++ b/drivers/mmc/host/sdhci.h
>>> @@ -42,6 +42,7 @@
>>>  #define  SDHCI_TRNS_BLK_CNT_EN       0x02
>>>  #define  SDHCI_TRNS_AUTO_CMD12       0x04
>>>  #define  SDHCI_TRNS_AUTO_CMD23       0x08
>>> +#define  SDHCI_TRNS_AUTO_SEL 0x0C
>>>  #define  SDHCI_TRNS_READ     0x10
>>>  #define  SDHCI_TRNS_MULTI    0x20
>>>
>>> @@ -185,6 +186,7 @@
>>>  #define   SDHCI_CTRL_DRV_TYPE_D              0x0030
>>>  #define  SDHCI_CTRL_EXEC_TUNING              0x0040
>>>  #define  SDHCI_CTRL_TUNED_CLK                0x0080
>>> +#define  SDHCI_CMD23_ENABLE          0x0800
>>>  #define  SDHCI_CTRL_V4_MODE          0x1000
>>>  #define  SDHCI_CTRL_64BIT_ADDR               0x2000
>>>  #define  SDHCI_CTRL_PRESET_VAL_ENABLE        0x8000
>>>
>>
>