Re: [PATCH v3 3/5] mmc: core: implement enhanced strobe support

[Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org>]

Hi

在 2016-5-20 8:18, Doug Anderson 写道:
> Hi,
>
> On Tue, May 10, 2016 at 2:09 AM, Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org> wrote:
>> Controllers use data strobe line to latch data from devices
>> under hs400 mode, but not for cmd line. So since emmc 5.1, JEDEC
>> introduces enhanced strobe mode for latching cmd response from
>> emmc devices to host controllers. This new feature is optional,
>> so it depends both on device's cap and host's cap to decide
>> whether to use it or not.
>
> I don't totally understand it, but two boards I'm working with have
> eMMC devices that claim to be eMMC 5.0 devices but also have support
> for strobe.  Did people just cherry-pick this feature from eMMC 5.1 to
> their eMMC 5.0 devices?

Presumably I guess your "support for strobe" means "support for
enhanced strobe", right?

hs400es is also optional for emmc 5.1, so it's impossible to find a
emmc 5.0 claiming to support hs400es.

Coud you share me the device's ID number on its package or from the
device's manual?


>
>
>> Signed-off-by: Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
>> ---
>>
>> Changes in v3: None
>> Changes in v2: None
>>
>>   drivers/mmc/core/bus.c   |  3 +-
>>   drivers/mmc/core/core.c  |  8 +++++
>>   drivers/mmc/core/mmc.c   | 79 ++++++++++++++++++++++++++++++++++++++++++++++--
>>   include/linux/mmc/card.h |  1 +
>>   include/linux/mmc/host.h | 11 +++++++
>>   include/linux/mmc/mmc.h  |  3 ++
>>   6 files changed, 102 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mmc/core/bus.c b/drivers/mmc/core/bus.c
>> index 4bc48f1..7e94b9d 100644
>> --- a/drivers/mmc/core/bus.c
>> +++ b/drivers/mmc/core/bus.c
>> @@ -332,12 +332,13 @@ int mmc_add_card(struct mmc_card *card)
>>                          mmc_card_ddr52(card) ? "DDR " : "",
>>                          type);
>>          } else {
>> -               pr_info("%s: new %s%s%s%s%s card at address %04x\n",
>> +               pr_info("%s: new %s%s%s%s%s%s card at address %04x\n",
>>                          mmc_hostname(card->host),
>>                          mmc_card_uhs(card) ? "ultra high speed " :
>>                          (mmc_card_hs(card) ? "high speed " : ""),
>>                          mmc_card_hs400(card) ? "HS400 " :
>>                          (mmc_card_hs200(card) ? "HS200 " : ""),
>> +                       mmc_card_hs400es(card) ? "Enhanced strobe" : "",
>
> Nit: there should be a space before the quote.  Otherwise the message
> runs together, like:
>
> new HS400 Enhanced strobeMMC card at address 0001

Good catch, thanks.

>
>
>>                          mmc_card_ddr52(card) ? "DDR " : "",
>>                          uhs_bus_speed_mode, type, card->rca);
>>          }
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index 99275e4..a559501 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -1127,6 +1127,14 @@ void mmc_set_initial_state(struct mmc_host *host)
>>          host->ios.bus_width = MMC_BUS_WIDTH_1;
>>          host->ios.timing = MMC_TIMING_LEGACY;
>>          host->ios.drv_type = 0;
>> +       host->ios.enhanced_strobe = false;
>> +
>> +       /*
>> +        * Make sure we are in non-enhanced strobe mode before we
>> +        * actually enable it in ext_csd.
>> +        */
>> +       if (host->ops->hs400_enhanced_strobe)
>> +               host->ops->hs400_enhanced_strobe(host, &host->ios);
>>
>>          mmc_set_ios(host);
>>   }
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index f99c47e..c2d1981 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -235,6 +235,11 @@ static void mmc_select_card_type(struct mmc_card *card)
>>                  avail_type |= EXT_CSD_CARD_TYPE_HS400_1_2V;
>>          }
>>
>> +       if ((caps2 & MMC_CAP2_HS400_ES) &&
>> +           card->ext_csd.strobe_support &&
>> +           (card_type & EXT_CSD_CARD_TYPE_HS400))
>> +               avail_type |= EXT_CSD_CARD_TYPE_HS400ES;
>> +
>>          card->ext_csd.hs_max_dtr = hs_max_dtr;
>>          card->ext_csd.hs200_max_dtr = hs200_max_dtr;
>>          card->mmc_avail_type = avail_type;
>> @@ -383,6 +388,7 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
>>                          mmc_card_set_blockaddr(card);
>>          }
>>
>> +       card->ext_csd.strobe_support = ext_csd[EXT_CSD_STROBE_SUPPORT];
>>          card->ext_csd.raw_card_type = ext_csd[EXT_CSD_CARD_TYPE];
>>          mmc_select_card_type(card);
>>
>> @@ -1216,6 +1222,73 @@ out_err:
>>          return err;
>>   }
>>
>> +static int mmc_select_hs400es(struct mmc_card *card)
>> +{
>> +       struct mmc_host *host = card->host;
>> +       int err = 0;
>> +       u8 val;
>> +
>> +       err = mmc_select_bus_width(card);
>> +       if (IS_ERR_VALUE(err))
>> +               goto out_err;
>> +
>> +       /* Switch card to HS mode */
>> +       err = mmc_select_hs(card);
>> +       if (err) {
>> +               pr_err("%s: switch to high-speed failed, err:%d\n",
>> +                       mmc_hostname(host), err);
>> +               goto out_err;
>> +       }
>> +
>> +       err = mmc_switch_status(card);
>> +       if (err)
>> +               goto out_err;
>> +
>> +       /* Switch card to DDR with strobe bit */
>> +       val = EXT_CSD_DDR_BUS_WIDTH_8 | EXT_CSD_BUS_WIDTH_STROBE;
>
> In the hs400 function earlier in the file the check to confirm that
> the bus width is 8 before doing this.  Should we do that here, too?

yes, will fix it. And we can just check host's cap to see
if it supports 8bit before mmc_select_bus_width because we don't
need to do anything without 8-bit support.

>
>> +       err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> +                        EXT_CSD_BUS_WIDTH,
>> +                        val,
>> +                        card->ext_csd.generic_cmd6_time);
>> +       if (err) {
>> +               pr_err("%s: switch to bus width for hs400es failed, err:%d\n",
>> +                       mmc_hostname(host), err);
>> +               goto out_err;
>> +       }
>> +
>> +       /* Switch card to HS400 */
>> +       val = EXT_CSD_TIMING_HS400 |
>> +             card->drive_strength << EXT_CSD_DRV_STR_SHIFT;
>> +       err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> +                          EXT_CSD_HS_TIMING, val,
>> +                          card->ext_csd.generic_cmd6_time,
>> +                          true, false, true);
>> +       if (err) {
>> +               pr_err("%s: switch to hs400es failed, err:%d\n",
>> +                       mmc_hostname(host), err);
>> +               goto out_err;
>> +       }
>> +
>> +       /* Set host controller to HS400 timing and frequency */
>> +       mmc_set_timing(host, MMC_TIMING_MMC_HS400);
>> +
>> +       /* Controller enable enhanced strobe function */
>> +       host->ios.enhanced_strobe = true;
>> +       if (host->ops->hs400_enhanced_strobe)
>> +               host->ops->hs400_enhanced_strobe(host, &host->ios);
>> +
>> +       err = mmc_switch_status(card);
>> +       if (err)
>> +               goto out_err;
>> +
>> +       return 0;
>> +
>> +out_err:
>> +       pr_err("%s: %s failed, error %d\n", mmc_hostname(card->host),
>> +              __func__, err);
>> +       return err;
>> +}
>> +
>>   static void mmc_select_driver_type(struct mmc_card *card)
>>   {
>>          int card_drv_type, drive_strength, drv_type;
>> @@ -1297,7 +1370,7 @@ err:
>>   }
>>
>>   /*
>> - * Activate High Speed or HS200 mode if supported.
>> + * Activate High Speed, HS200 or HS400ES mode if supported.
>>    */
>>   static int mmc_select_timing(struct mmc_card *card)
>>   {
>> @@ -1306,7 +1379,9 @@ static int mmc_select_timing(struct mmc_card *card)
>>          if (!mmc_can_ext_csd(card))
>>                  goto bus_speed;
>>
>> -       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
>> +       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)
>> +               err = mmc_select_hs400es(card);
>> +       else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
>>                  err = mmc_select_hs200(card);
>>          else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
>>                  err = mmc_select_hs(card);
>> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
>> index eb0151b..22defc2 100644
>> --- a/include/linux/mmc/card.h
>> +++ b/include/linux/mmc/card.h
>> @@ -95,6 +95,7 @@ struct mmc_ext_csd {
>>          u8                      raw_partition_support;  /* 160 */
>>          u8                      raw_rpmb_size_mult;     /* 168 */
>>          u8                      raw_erased_mem_count;   /* 181 */
>> +       u8                      strobe_support;         /* 184 */
>>          u8                      raw_ext_csd_structure;  /* 194 */
>>          u8                      raw_card_type;          /* 196 */
>>          u8                      raw_driver_strength;    /* 197 */
>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>> index 2a06fb0..f98bd0e 100644
>> --- a/include/linux/mmc/host.h
>> +++ b/include/linux/mmc/host.h
>> @@ -19,6 +19,7 @@
>>
>>   #include <linux/mmc/core.h>
>>   #include <linux/mmc/card.h>
>> +#include <linux/mmc/mmc.h>
>>   #include <linux/mmc/pm.h>
>>
>>   struct mmc_ios {
>> @@ -77,6 +78,8 @@ struct mmc_ios {
>>   #define MMC_SET_DRIVER_TYPE_A  1
>>   #define MMC_SET_DRIVER_TYPE_C  2
>>   #define MMC_SET_DRIVER_TYPE_D  3
>> +
>> +       bool enhanced_strobe;                   /* hs400es selection */
>>   };
>>
>>   struct mmc_host_ops {
>> @@ -143,6 +146,9 @@ struct mmc_host_ops {
>>
>>          /* Prepare HS400 target operating frequency depending host driver */
>>          int     (*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
>> +       /* Prepare enhanced strobe depending host driver */
>> +       void    (*hs400_enhanced_strobe)(struct mmc_host *host,
>> +                                        struct mmc_ios *ios);
>>          int     (*select_drive_strength)(struct mmc_card *card,
>>                                           unsigned int max_dtr, int host_drv,
>>                                           int card_drv, int *drv_type);
>> @@ -513,6 +519,11 @@ static inline bool mmc_card_hs400(struct mmc_card *card)
>>          return card->host->ios.timing == MMC_TIMING_MMC_HS400;
>>   }
>>
>> +static inline bool mmc_card_hs400es(struct mmc_card *card)
>> +{
>> +       return card->host->ios.enhanced_strobe == true;
>
> nit: never need "== true".  Just:
>
>    return card->host->ios.enhanced_strobe;
>

yes, thanks.

>> +}
>> +
>>   void mmc_retune_timer_stop(struct mmc_host *host);
>>
>>   static inline void mmc_retune_needed(struct mmc_host *host)
>> diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
>> index 15f2c4a..c376209 100644
>> --- a/include/linux/mmc/mmc.h
>> +++ b/include/linux/mmc/mmc.h
>> @@ -297,6 +297,7 @@ struct _mmc_csd {
>>   #define EXT_CSD_PART_CONFIG            179     /* R/W */
>>   #define EXT_CSD_ERASED_MEM_CONT                181     /* RO */
>>   #define EXT_CSD_BUS_WIDTH              183     /* R/W */
>> +#define EXT_CSD_STROBE_SUPPORT         184     /* RO */
>>   #define EXT_CSD_HS_TIMING              185     /* R/W */
>>   #define EXT_CSD_POWER_CLASS            187     /* R/W */
>>   #define EXT_CSD_REV                    192     /* RO */
>> @@ -380,12 +381,14 @@ struct _mmc_csd {
>>   #define EXT_CSD_CARD_TYPE_HS400_1_2V   (1<<7)  /* Card can run at 200MHz DDR, 1.2V */
>>   #define EXT_CSD_CARD_TYPE_HS400                (EXT_CSD_CARD_TYPE_HS400_1_8V | \
>>                                           EXT_CSD_CARD_TYPE_HS400_1_2V)
>> +#define EXT_CSD_CARD_TYPE_HS400ES      (1<<8)  /* Card can run at HS400ES */
>>
>>   #define EXT_CSD_BUS_WIDTH_1    0       /* Card is in 1 bit mode */
>>   #define EXT_CSD_BUS_WIDTH_4    1       /* Card is in 4 bit mode */
>>   #define EXT_CSD_BUS_WIDTH_8    2       /* Card is in 8 bit mode */
>>   #define EXT_CSD_DDR_BUS_WIDTH_4        5       /* Card is in 4 bit DDR mode */
>>   #define EXT_CSD_DDR_BUS_WIDTH_8        6       /* Card is in 8 bit DDR mode */
>> +#define EXT_CSD_BUS_WIDTH_STROBE BIT(7)        /* Enhanced strobe mode */
>
> nit: while your code should be OK, it seems better to be BIT(3), since
> above is really:
>

I don't unstand here. EXT_CSD_BUS_WIDTH_STROBE is the MSB of
BUS_WIDTH[183] which is a 8-bit reg.


> 0
> BIT(0)
> BIT(1)
> BIT(2) | BIT(0)
> BIT(2) | BIT(1)
>
> ...at least that's my understanding...
>
>
>

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