Re: [PATCH V8] mmc: core: Add Power Off Notify Feature eMMC 4.5

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On 14 October 2011 03:41, Chris Ball <cjb@xxxxxxxxxx> wrote:
> Hi Girish, just trivial changes below.
>
> Does anyone have a Tested-by: to add to the patch?
No not yet.
>
> On Thu, Oct 13 2011, Girish K S wrote:
>> This patch adds the support for power off notify feature, available in
>> eMMC 4.5 devices. If the the host has support for this feature, then the
>> mmc core will notify it to the device by setting the POWER_OFF_NOTIFICATION
>> byte in the extended csd register with a value 1(POWER_ON).
>>
>> For suspend mode short timeout is used, whereas for the normal poweroff long
>> timeout is used.
>> cc: Chris Ball <cjb@xxxxxxxxxx>
>> Signed-off-by: Girish K S <girish.shivananjappa@xxxxxxxxxx>
>> Signed-off-by: Jaehoon Chung <jh80.chung@xxxxxxxxxxx>
>> ---
>> Changes in V8:
>>       Updated with review comments of Chris Ball and rebased to
>>       chris-mmc/mmc-next branch.
>> Changes in V7:
>>       Rebased to chris-mmc/mmc-next branch. merged to patches
>>       to single patch.
>> Changes in V6:
>>       Fixes checkpatch errors. The patches are generated after
>>       rebasing to chris's mmc-next branch.
>> Changes in V5:
>>       This patch version fixes the problem with power off
>>       notify function, when called for the first time and
>>       card is not yet initialised.
>> Changes in V4:
>>       Updated with review comments of Jeon
>> Changes in V2:
>>       Adds poweroff notification handling in suspend/normal.
>>
>>  drivers/mmc/core/core.c  |   36 ++++++++++++++++++++++++++++++++++++
>>  drivers/mmc/core/mmc.c   |   23 +++++++++++++++++++++--
>>  drivers/mmc/host/sdhci.c |    9 +++++++++
>>  include/linux/mmc/card.h |    6 ++++++
>>  include/linux/mmc/host.h |    6 ++++++
>>  include/linux/mmc/mmc.h  |    8 ++++++++
>>  6 files changed, 86 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index 61d7730..db368b2 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -1212,11 +1212,45 @@ static void mmc_power_up(struct mmc_host *host)
>>
>>  void mmc_power_off(struct mmc_host *host)
>>  {
>> +     struct mmc_card *card;
>
> struct mmc_card *card = host->card;
>
>> +     unsigned int notify_type;
>> +     unsigned int timeout;
>> +     int err;
>> +
>> +     BUG_ON(!host);
>
> Not necessary.
OK
>
>> +
>>       mmc_host_clk_hold(host);
>>
>> +     card = host->card;
>>       host->ios.clock = 0;
>>       host->ios.vdd = 0;
>>
>> +     if (card != NULL && mmc_card_mmc(card) &&
>
> != NULL is unnecessary.
This is required. Let me explain the scenario where i felt it is necessary.

The card resource will be allocated when the delayed work is scheduled
i.e.(on invocation of the function mmc_rescan)
The call trace for card instance creation is given below in the called
sequence. mmc_rescan->mmc_rescan_try_freq->mmc_attach_mmc->mmc_init_card.

Before the above card resource is allocated, the power_off function is
invoked in the  function mmc_start_host (invoked by the add_host)
At this point of time the card == NULL and system crashes. So i check
for NULL first and then the card state.
>
>> +         (card->poweroff_notify_state == MMC_POWERED_ON)) {
>
> Extra set of parens unnecessary.
OK
>
>> +
>> +             if (host->power_notify_type == MMC_HOST_PW_NOTIFY_SHORT) {
>> +                     notify_type = EXT_CSD_POWER_OFF_SHORT;
>> +                     timeout = card->ext_csd.generic_cmd6_time;
>> +                     card->poweroff_notify_state = MMC_POWEROFF_SHORT;
>> +             } else {
>> +                     notify_type = EXT_CSD_POWER_OFF_LONG;
>> +                     timeout = card->ext_csd.power_off_longtime;
>> +                     card->poweroff_notify_state = MMC_POWEROFF_LONG;
>> +             }
>> +
>> +             err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> +                              EXT_CSD_POWER_OFF_NOTIFICATION,
>> +                              notify_type, timeout);
>> +
>> +             if (err && err != -EBADMSG)
>> +                     pr_err("Device failed to respond within %d poweroff "
>> +                            "time. Forcefully powering down the device\n",
>> +                            timeout);
>> +
>> +             /* Set the card state to no notification after the poweroff */
>> +             card->poweroff_notify_state = MMC_NO_POWER_NOTIFICATION;
>> +     }
>> +
>>       /*
>>        * Reset ocr mask to be the highest possible voltage supported for
>>        * this mmc host. This value will be used at next power up.
>> @@ -2208,6 +2242,7 @@ int mmc_pm_notify(struct notifier_block *notify_block,
>>
>>               spin_lock_irqsave(&host->lock, flags);
>>               host->rescan_disable = 1;
>> +             host->power_notify_type = MMC_HOST_PW_NOTIFY_SHORT;
>>               spin_unlock_irqrestore(&host->lock, flags);
>>               cancel_delayed_work_sync(&host->detect);
>>
>> @@ -2231,6 +2266,7 @@ int mmc_pm_notify(struct notifier_block *notify_block,
>>
>>               spin_lock_irqsave(&host->lock, flags);
>>               host->rescan_disable = 0;
>> +             host->power_notify_type = MMC_HOST_PW_NOTIFY_LONG;
>>               spin_unlock_irqrestore(&host->lock, flags);
>>               mmc_detect_change(host, 0);
>>
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index 4e869d3..f8ea938 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -458,10 +458,12 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
>>       else
>>               card->erased_byte = 0x0;
>>
>> -     if (card->ext_csd.rev >= 6)
>> +     if (card->ext_csd.rev >= 6) {
>>               card->ext_csd.generic_cmd6_time = 10 *
>>                       ext_csd[EXT_CSD_GENERIC_CMD6_TIME];
>> -     else
>> +             card->ext_csd.power_off_longtime = 10 *
>> +                     ext_csd[EXT_CSD_POWER_OFF_LONG_TIME];
>> +     } else
>>               card->ext_csd.generic_cmd6_time = 0;
>>
>>  out:
>> @@ -846,6 +848,23 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>>       }
>>
>>       /*
>> +      * If the host supports the power_off_notify capability then
>> +      * set the notification byte in the ext_csd register of device
>> +      */
>> +     if ((host->caps2 & MMC_CAP2_POWEROFF_NOTIFY) &&
>> +         (card->poweroff_notify_state == MMC_NO_POWER_NOTIFICATION)) {
>> +             err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> +                              EXT_CSD_POWER_OFF_NOTIFICATION,
>> +                              EXT_CSD_POWER_ON,
>> +                              card->ext_csd.generic_cmd6_time);
>> +             if (err && err != -EBADMSG)
>> +                     goto free_card;
>> +     }
>> +
>> +     if (!err)
>> +             card->poweroff_notify_state = MMC_POWERED_ON;
>> +
>> +     /*
>>        * Activate high speed (if supported)
>>        */
>>       if ((card->ext_csd.hs_max_dtr != 0) &&
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 2cc3ffa..91fdaed 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -2739,6 +2739,15 @@ int sdhci_add_host(struct sdhci_host *host)
>>       if (caps[1] & SDHCI_DRIVER_TYPE_D)
>>               mmc->caps |= MMC_CAP_DRIVER_TYPE_D;
>>
>> +     /*
>> +      * If Notify capability is enabled by the host, set notify to
>> +      * short power off notify timeout value.
>> +      */
>> +     if (mmc->caps2 & MMC_CAP2_POWEROFF_NOTIFY)
>> +             mmc->power_notify_type = MMC_HOST_PW_NOTIFY_SHORT;
>> +     else
>> +             mmc->power_notify_type = MMC_HOST_PW_NOTIFY_NONE;
>> +
>>       /* Initial value for re-tuning timer count */
>>       host->tuning_count = (caps[1] & SDHCI_RETUNING_TIMER_COUNT_MASK) >>
>>                             SDHCI_RETUNING_TIMER_COUNT_SHIFT;
>> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
>> index 30d493c..fce88b3 100644
>> --- a/include/linux/mmc/card.h
>> +++ b/include/linux/mmc/card.h
>> @@ -54,6 +54,7 @@ struct mmc_ext_csd {
>>       unsigned int            part_time;              /* Units: ms */
>>       unsigned int            sa_timeout;             /* Units: 100ns */
>>       unsigned int            generic_cmd6_time;      /* Units: 10ms */
>> +     unsigned int            power_off_longtime;     /* Units: ms */
>>       unsigned int            hs_max_dtr;
>>       unsigned int            sectors;
>>       unsigned int            card_type;
>> @@ -209,6 +210,11 @@ struct mmc_card {
>>  #define MMC_QUIRK_BLK_NO_CMD23       (1<<7)          /* Avoid CMD23 for regular multiblock */
>>  #define MMC_QUIRK_BROKEN_BYTE_MODE_512 (1<<8)        /* Avoid sending 512 bytes in */
>>                                               /* byte mode */
>> +     unsigned int    poweroff_notify_state;  /* eMMC4.5 notify feature */
>> +#define MMC_NO_POWER_NOTIFICATION    0
>> +#define MMC_POWERED_ON                       1
>> +#define MMC_POWEROFF_SHORT           2
>> +#define MMC_POWEROFF_LONG            3
>>
>>       unsigned int            erase_size;     /* erase size in sectors */
>>       unsigned int            erase_shift;    /* if erase unit is power 2 */
>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>> index aed5bc7..65c47fc 100644
>> --- a/include/linux/mmc/host.h
>> +++ b/include/linux/mmc/host.h
>> @@ -239,8 +239,14 @@ struct mmc_host {
>>       unsigned int            caps2;          /* More host capabilities */
>>
>>  #define MMC_CAP2_BOOTPART_NOACC      (1 << 0)        /* Boot partition no access */
>> +#define MMC_CAP2_CACHE_CTRL  (1 << 1)        /* Allow cache control. */
>> +#define MMC_CAP2_POWEROFF_NOTIFY (1 << 2)    /* Notify poweroff supported */
>>
>>       mmc_pm_flag_t           pm_caps;        /* supported pm features */
>> +     unsigned int        power_notify_type;
>
> You can align "power_notify_type" alongside "pm_caps" here.
OK
>
> Thanks,
>
> - Chris.
> --
> Chris Ball   <cjb@xxxxxxxxxx>   <http://printf.net/>
> One Laptop Per Child
>
Thanks for the comments. please let me know if something wrong with my
above justification. Or any alternative for the same

regards
Girish K S
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