Re: [PATCH] mmc: support BKOPS feature for eMMC

[Jaehoon Chung <jh80.chung@samsung.com>]

Hi Sebastian.

On 10/28/2011 04:26 AM, Sebastian Rasmussen wrote:

>> Background operation(BKOPS) is one of eMMC's features.
>>
>> If set the URGENT_BKOPS in response, we can notify that card nedd the BKOPS.
>> And all I/O request is done, then run background operation.
>> If request read/write operation during BKOPS, issue HPI interrupt.
>>
>> If you want to use this feature, should be set MMC_CAP2_BKOPS.
> 
> Enable eMMC background operations (BKOPS) feature.
> 
> If URGENT_BKOPS is set after a response, note that BKOPS
> are required. After all I/O requests are finished, run
> BKOPS if required. Should read/write operations be requested
> during BKOPS, first issue HPI to interrupt the ongoing BKOPS
> and then service the request.
> 
> If you want to enable this feature, set MMC_CAP2_BKOPS.
> 
>>
>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
>> CC: Hanumath Prasad <hanumath.prasad@stericsson.com>
>> ---
>>  drivers/mmc/card/block.c   |   13 +++++++-
>>  drivers/mmc/card/queue.c   |    1 +
>>  drivers/mmc/core/core.c    |   77 ++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/mmc/core/mmc.c     |   21 ++++++++++++
>>  drivers/mmc/core/mmc_ops.c |    4 ++
>>  include/linux/mmc/card.h   |   11 ++++++
>>  include/linux/mmc/core.h   |    2 +
>>  include/linux/mmc/host.h   |    1 +
>>  include/linux/mmc/mmc.h    |    4 ++
>>  9 files changed, 133 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>> index 4fd5723..edbed7a 100644
>> --- a/drivers/mmc/card/block.c
>> +++ b/drivers/mmc/card/block.c
>> @@ -1185,14 +1185,25 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc)
>>                type = rq_data_dir(req) == READ ? MMC_BLK_READ : MMC_BLK_WRITE;
>>                mmc_queue_bounce_post(mq_rq);
>>
>> +               if (mmc_card_doing_bkops(card)) {
>> +                       if (mmc_interrupt_bkops(card))
>> +                               goto cmd_abort;
>> +               }
>> +
>>                switch (status) {
>>                case MMC_BLK_SUCCESS:
>>                case MMC_BLK_PARTIAL:
>> +                       spin_lock_irq(&md->lock);
>> +                       /*
>> +                        * Check BKOPS urgency from each R1 response
>> +                        */
>> +                       if (mmc_card_mmc(card) &&
>> +                               (brq->cmd.resp[0] & R1_URGENT_BKOPS))
>> +                               mmc_card_set_need_bkops(card);
> 
> First of all, R1_URGENT_BKOPS is fine to check in cmd->resp[0], but it
> is only valid if cmd->resp contains an R1 or an R1b response. Granted,
> commands that do not have R1/R1b responses are few, but I still
> believe you need to check that with mmc_resp_type().

Ok...i will add to check for mmc_resp_type().

> 
> Moreover in the eMMC 4.41 spec it was ok to check bit 6 of the status
> (which is what you do above) as that bit corresponded to URGENT_BKOPS.
> However for eMMC 4.5 this bit has been combined with other kinds of of
> exceptional situations. The bit has been renamed EXCEPTION_EVENT and
> if it is set you then need to read (using CMD8) bytes 55:54 in EXT_CSD
> named EXCEPTION_EVENTS_STATUS where bit 0 indicates URGENT_BKOPS.

Right..eMMC4.5 is modified them. So host need to check EXCEPTION_EVENTS_STATUS and
whenever need to check, host should read the ext_csd register. right?
I will modify also this point..(actually..this patch is based on eMMC4.41)

> 
> So I you need to check card->ext_csd.rev here to know what method you
> need to apply to determine if BKOPS are urgent or not.
> 
>>                        /*
>>                         * A block was successfully transferred.
>>                         */
>>                        mmc_blk_reset_success(md, type);
>> -                       spin_lock_irq(&md->lock);
>>                        ret = __blk_end_request(req, 0,
>>                                                brq->data.bytes_xfered);
>>                        spin_unlock_irq(&md->lock);
>> diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
>> index dcad59c..31e5eca 100644
>> --- a/drivers/mmc/card/queue.c
>> +++ b/drivers/mmc/card/queue.c
>> @@ -68,6 +68,7 @@ static int mmc_queue_thread(void *d)
>>                                set_current_state(TASK_RUNNING);
>>                                break;
>>                        }
>> +                       mmc_start_bkops(mq->card);
>>                        up(&mq->thread_sem);
>>                        schedule();
>>                        down(&mq->thread_sem);
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index 5278ffb..7ef270d 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -238,6 +238,50 @@ mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>>        host->ops->request(host, mrq);
>>  }
>>
>> +/**
>> + *     mmc_start_bkops - start BKOPS for supported cards
>> + *     @card: MMC card to start BKOPS
>> + *
>> + *     Start background operations whenever requested.
>> + *     when the urgent BKOPS bit is set in a R1 command response
>> + *     then background operations should be started immediately.
>> +*/
>> +void mmc_start_bkops(struct mmc_card *card)
>> +{
>> +       int err;
>> +       unsigned long flags;
>> +
>> +       if ((!card || !card->ext_csd.bkops_en) &&
>> +                       !(card->host->caps2 & MMC_CAP2_BKOPS))
>> +               return;
>> +
>> +       /*
>> +        * If card is already doing bkops or need for
>> +        * bkops flag is not set, then do nothing just
>> +        * return
>> +        */
>> +       if (mmc_card_doing_bkops(card)
>> +                       || !mmc_card_need_bkops(card))
>> +               return;
>> +
>> +       mmc_claim_host(card->host);
>> +       err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> +                       EXT_CSD_BKOPS_START, 1, 0);
>> +       if (err) {
>> +               pr_warning("error %d starting bkops\n", err);
>> +               mmc_card_clr_need_bkops(card);
>> +               goto out;
>> +       }
>> +       spin_lock_irqsave(&card->host->lock, flags);
>> +       mmc_card_clr_need_bkops(card);
>> +       mmc_card_set_doing_bkops(card);
>> +       spin_unlock_irqrestore(&card->host->lock, flags);
>> +out:
>> +       mmc_release_host(card->host);
>> +}
>> +EXPORT_SYMBOL(mmc_start_bkops);
>> +
>> +
>>  static void mmc_wait_done(struct mmc_request *mrq)
>>  {
>>        complete(&mrq->completion);
>> @@ -466,6 +510,39 @@ int mmc_wait_for_cmd(struct mmc_host *host, struct mmc_command *cmd, int retries
>>  EXPORT_SYMBOL(mmc_wait_for_cmd);
>>
>>  /**
>> + *     mmc_interrupt_bkops - interrupt ongoing BKOPS
>> + *     @card: MMC card to check BKOPS
>> + *
>> + *     Send HPI command to interrupt ongoing background operations,
>> + *     to allow rapid servicing of foreground operations,e.g. read/
>> + *     writes. Wait until the card comes out of the programming state
>> + *     to avoid errors in servicing read/write requests.
>> + */
>> +int mmc_interrupt_bkops(struct mmc_card *card)
>> +{
>> +       int err;
>> +       unsigned long flags;
>> +       u32 status;
>> +
>> +       BUG_ON(!card);
>> +
>> +       /* send HPI to interrupt BKOPS. */
>> +       err = mmc_send_hpi_cmd(card, &status);
>> +       if (err || R1_CURRENT_STATE(status) == 7) {
>> +               do {
>> +                       err = mmc_send_status(card, &status);
>> +                       if (err)
>> +                               return err;
>> +               } while (R1_CURRENT_STATE(status) == 7);
>> +       }
>> +       spin_lock_irqsave(&card->host->lock, flags);
>> +       mmc_card_clr_doing_bkops(card);
>> +       spin_unlock_irqrestore(&card->host->lock, flags);
>> +       return 0;
>> +}
>> +EXPORT_SYMBOL(mmc_interrupt_bkops);
>> +
>> +/**
>>  *     mmc_set_data_timeout - set the timeout for a data command
>>  *     @data: data phase for command
>>  *     @card: the MMC card associated with the data transfer
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index 3627044..b16db45 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -448,6 +448,10 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
>>        }
>>
>>        if (card->ext_csd.rev >= 5) {
>> +               /* check whether the eMMC card support BKOPS */
>> +               if (ext_csd[EXT_CSD_BKOPS_SUPPORT] & 0x1)
>> +                       card->ext_csd.bkops = 1;
> 
> How about this to include/linux/mmc/mmc.h and using it here?
> 
> #define EXT_CSD_BKOPS_SUPPORTED BIT(0)
> 
> BTW, this is required starting from eMMC 4.5.

Consider your opinion..:)

> 
>> +
>>                /* check whether the eMMC card supports HPI */
>>                if (ext_csd[EXT_CSD_HPI_FEATURES] & 0x1) {
>>                        card->ext_csd.hpi = 1;
>> @@ -909,6 +913,23 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>>        }
>>
>>        /*
>> +        * enable BKOPS feature (if supported)
>> +        */
>> +       if (card->ext_csd.bkops) {
>> +               err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> +                       EXT_CSD_BKOPS_EN, 1, 0);
> 
> The BKOPS_EN property in EXT_CSD is labelled R/W which means that it
> is one time programmable. Therefore it makes no sense to write this
> every time you are initializing an eMMC. What you could do is to read
> BKOPS_EN to determine if BKOPS should, according to the eMMC, be
> enabled in the MMC framework.

Then this code is unnecessary..because card supported bkops, EXT_CSD_BKOPS_EN is set by default.
And if user want to use BKOPS,user can use IOCTL like you mentioned.

> 
> According to other discussions here it seems to me as if Chris and
> others are wary of having sysfs-files enable users to write to
> one-time programmable registers. So therefore I guess the only option
> is to use the generic MMC command passthrough in mmc_blk_ioctl() to do
> such things.
> 
>> +               if (err && err != -EBADMSG)
>> +                       goto free_card;
>> +
>> +               if (err) {
>> +                       pr_warning("%s: Enabling BKOPS failed\n",
>> +                               mmc_hostname(card->host));
>> +                       err = 0;
>> +               } else
>> +                       card->ext_csd.bkops_en = 1;
>> +       }
>> +
>> +       /*
>>         * Enable HPI feature (if supported)
>>         */
>>        if (card->ext_csd.hpi) {
>> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
>> index 007863e..7653e33 100644
>> --- a/drivers/mmc/core/mmc_ops.c
>> +++ b/drivers/mmc/core/mmc_ops.c
>> @@ -398,6 +398,10 @@ int mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
>>        if (err)
>>                return err;
>>
>> +       /* No need to check card status in case of BKOPS switch*/
>> +       if (index == EXT_CSD_BKOPS_START)
>> +               return 0;
> 
> Why is this not needed? I can see why you wouldn't want to wait until
> the card is no longer busy (as it will stay busy until BKOPS are no
> longer needed), but the bits indicating errors must surely be
> interesting to check?

I think that didn't need to check because just write any value in EXT_CSD_BKOPS_START.

> 
>> +
>>        /* Must check status to be sure of no errors */
>>        do {
>>                err = mmc_send_status(card, &status);
>> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
>> index 6e04e10..f4abb7c 100644
>> --- a/include/linux/mmc/card.h
>> +++ b/include/linux/mmc/card.h
>> @@ -71,6 +71,8 @@ struct mmc_ext_csd {
>>        bool                    hpi_en;                 /* HPI enablebit */
>>        bool                    hpi;                    /* HPI support bit */
>>        unsigned int            hpi_cmd;                /* cmd used as HPI */
>> +       bool                    bkops;          /* background support bit */
>> +       bool                    bkops_en;       /* background enable bit */
>>        u8                      raw_partition_support;  /* 160 */
>>        u8                      raw_erased_mem_count;   /* 181 */
>>        u8                      raw_ext_csd_structure;  /* 194 */
>> @@ -206,6 +208,8 @@ struct mmc_card {
>>  #define MMC_STATE_HIGHSPEED_DDR (1<<4)         /* card is in high speed mode */
>>  #define MMC_STATE_ULTRAHIGHSPEED (1<<5)                /* card is in ultra high speed mode */
>>  #define MMC_CARD_SDXC          (1<<6)          /* card is SDXC */
>> +#define MMC_STATE_NEED_BKOPS   (1<<7)          /* card need to do BKOPS */
>> +#define MMC_STATE_DOING_BKOPS  (1<<8)          /* card is doing BKOPS */
>>        unsigned int            quirks;         /* card quirks */
>>  #define MMC_QUIRK_LENIENT_FN0  (1<<0)          /* allow SDIO FN0 writes outside of the VS CCCR range */
>>  #define MMC_QUIRK_BLKSZ_FOR_BYTE_MODE (1<<1)   /* use func->cur_blksize */
>> @@ -365,6 +369,8 @@ static inline void __maybe_unused remove_quirk(struct mmc_card *card, int data)
>>  #define mmc_card_ddr_mode(c)   ((c)->state & MMC_STATE_HIGHSPEED_DDR)
>>  #define mmc_sd_card_uhs(c) ((c)->state & MMC_STATE_ULTRAHIGHSPEED)
>>  #define mmc_card_ext_capacity(c) ((c)->state & MMC_CARD_SDXC)
>> +#define mmc_card_need_bkops(c) ((c)->state & MMC_STATE_NEED_BKOPS)
>> +#define mmc_card_doing_bkops(c)        ((c)->state & MMC_STATE_DOING_BKOPS)
>>
>>  #define mmc_card_set_present(c)        ((c)->state |= MMC_STATE_PRESENT)
>>  #define mmc_card_set_readonly(c) ((c)->state |= MMC_STATE_READONLY)
>> @@ -373,6 +379,11 @@ static inline void __maybe_unused remove_quirk(struct mmc_card *card, int data)
>>  #define mmc_card_set_ddr_mode(c) ((c)->state |= MMC_STATE_HIGHSPEED_DDR)
>>  #define mmc_sd_card_set_uhs(c) ((c)->state |= MMC_STATE_ULTRAHIGHSPEED)
>>  #define mmc_card_set_ext_capacity(c) ((c)->state |= MMC_CARD_SDXC)
>> +#define mmc_card_set_need_bkops(c)     ((c)->state |= MMC_STATE_NEED_BKOPS)
>> +#define mmc_card_set_doing_bkops(c)    ((c)->state |= MMC_STATE_DOING_BKOPS)
>> +
>> +#define mmc_card_clr_need_bkops(c)     ((c)->state &= ~MMC_STATE_NEED_BKOPS)
>> +#define mmc_card_clr_doing_bkops(c)    ((c)->state &= ~MMC_STATE_DOING_BKOPS)
>>
>>  /*
>>  * Quirk add/remove for MMC products.
>> diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
>> index 174a844..600a177 100644
>> --- a/include/linux/mmc/core.h
>> +++ b/include/linux/mmc/core.h
>> @@ -134,6 +134,7 @@ struct mmc_host;
>>  struct mmc_card;
>>  struct mmc_async_req;
>>
>> +extern int mmc_interrupt_bkops(struct mmc_card *);
>>  extern struct mmc_async_req *mmc_start_req(struct mmc_host *,
>>                                           struct mmc_async_req *, int *);
>>  extern int mmc_interrupt_hpi(struct mmc_card *);
>> @@ -163,6 +164,7 @@ extern int mmc_can_sanitize(struct mmc_card *card);
>>  extern int mmc_can_secure_erase_trim(struct mmc_card *card);
>>  extern int mmc_erase_group_aligned(struct mmc_card *card, unsigned int from,
>>                                   unsigned int nr);
>> +extern void mmc_start_bkops(struct mmc_card *card);
>>  extern unsigned int mmc_calc_max_discard(struct mmc_card *card);
>>
>>  extern int mmc_set_blocklen(struct mmc_card *card, unsigned int blocklen);
>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>> index a3ac9c4..692e5f6 100644
>> --- a/include/linux/mmc/host.h
>> +++ b/include/linux/mmc/host.h
>> @@ -242,6 +242,7 @@ struct mmc_host {
>>  #define MMC_CAP2_CACHE_CTRL    (1 << 1)        /* Allow cache control */
>>  #define MMC_CAP2_POWEROFF_NOTIFY (1 << 2)      /* Notify poweroff supported */
>>  #define MMC_CAP2_NO_MULTI_READ (1 << 3)        /* Multiblock reads don't work */
>> +#define MMC_CAP2_BKOPS         (1 << 4)        /* BKOPS supported */
>>
>>        mmc_pm_flag_t           pm_caps;        /* supported pm features */
>>        unsigned int        power_notify_type;
>> diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
>> index 0e71356..283b848 100644
>> --- a/include/linux/mmc/mmc.h
>> +++ b/include/linux/mmc/mmc.h
>> @@ -138,6 +138,7 @@ static inline bool mmc_op_multi(u32 opcode)
>>  #define R1_CURRENT_STATE(x)    ((x & 0x00001E00) >> 9) /* sx, b (4 bits) */
>>  #define R1_READY_FOR_DATA      (1 << 8)        /* sx, a */
>>  #define R1_SWITCH_ERROR                (1 << 7)        /* sx, c */
>> +#define R1_URGENT_BKOPS                (1 << 6)        /* sx, a */
>>  #define R1_APP_CMD             (1 << 5)        /* sr, c */
>>
>>  #define R1_STATE_IDLE  0
>> @@ -278,6 +279,8 @@ struct _mmc_csd {
>>  #define EXT_CSD_PARTITION_SUPPORT      160     /* RO */
>>  #define EXT_CSD_HPI_MGMT               161     /* R/W */
>>  #define EXT_CSD_RST_N_FUNCTION         162     /* R/W */
>> +#define EXT_CSD_BKOPS_EN               163     /* R/W */
>> +#define EXT_CSD_BKOPS_START            164     /* W */
>>  #define EXT_CSD_SANITIZE_START         165     /* W */
>>  #define EXT_CSD_WR_REL_PARAM           166     /* RO */
>>  #define EXT_CSD_ERASE_GROUP_DEF                175     /* R/W */
>> @@ -313,6 +316,7 @@ struct _mmc_csd {
>>  #define EXT_CSD_POWER_OFF_LONG_TIME    247     /* RO */
>>  #define EXT_CSD_GENERIC_CMD6_TIME      248     /* RO */
>>  #define EXT_CSD_CACHE_SIZE             249     /* RO, 4 bytes */
>> +#define EXT_CSD_BKOPS_SUPPORT          502     /* RO */
>>  #define EXT_CSD_HPI_FEATURES           503     /* RO */
>>
>>  /*
>> --
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