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Subject: Re: [PATCH V4 1/2] scsi: ufs: Add DeepSleep feature
To:     Can Guo <cang@codeaurora.org>
Cc:     "Martin K . Petersen" <martin.petersen@oracle.com>,
        "James E . J . Bottomley" <jejb@linux.ibm.com>,
        linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        Bean Huo <huobean@gmail.com>,
        Stanley Chu <stanley.chu@mediatek.com>
References: <20201103141403.2142-1-adrian.hunter@intel.com>
 <20201103141403.2142-2-adrian.hunter@intel.com>
 <5331559186b4ecf5e5ffc1bf1d28c6b3@codeaurora.org>
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: <f3195f76-e81f-393e-a32e-3d06eaa10aeb@intel.com>
Date:   Wed, 4 Nov 2020 10:37:56 +0200
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On 4/11/20 10:29 am, Can Guo wrote:
> Hi Adrian,
> 
> On 2020-11-03 22:14, Adrian Hunter wrote:
>> DeepSleep is a UFS v3.1 feature that achieves the lowest power consumption
>> of the device, apart from power off.
>>
>> In DeepSleep mode, no commands are accepted, and the only way to exit is
>> using a hardware reset or power cycle.
>>
>> This patch assumes that if a power cycle was an option, then power off
>> would be preferable, so only exit via a hardware reset is supported.
>>
>> Drivers that wish to support DeepSleep need to set a new capability flag
>> UFSHCD_CAP_DEEPSLEEP and provide a hardware reset via the existing
>>  ->device_reset() callback.
>>
>> It is assumed that UFS devices with wspecversion >= 0x310 support
>> DeepSleep.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
>> ---
>>  Documentation/ABI/testing/sysfs-driver-ufs | 34 +++++++++++--------
>>  drivers/scsi/ufs/ufs-sysfs.c               |  7 ++++
>>  drivers/scsi/ufs/ufs.h                     |  1 +
>>  drivers/scsi/ufs/ufshcd.c                  | 39 ++++++++++++++++++++--
>>  drivers/scsi/ufs/ufshcd.h                  | 17 +++++++++-
>>  include/trace/events/ufs.h                 |  3 +-
>>  6 files changed, 83 insertions(+), 18 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-driver-ufs
>> b/Documentation/ABI/testing/sysfs-driver-ufs
>> index adc0d0e91607..e77fa784d6d8 100644
>> --- a/Documentation/ABI/testing/sysfs-driver-ufs
>> +++ b/Documentation/ABI/testing/sysfs-driver-ufs
>> @@ -916,21 +916,24 @@ Date:        September 2014
>>  Contact:    Subhash Jadavani <subhashj@codeaurora.org>
>>  Description:    This entry could be used to set or show the UFS device
>>          runtime power management level. The current driver
>> -        implementation supports 6 levels with next target states:
>> +        implementation supports 7 levels with next target states:
>>
>>          ==  ====================================================
>> -        0   an UFS device will stay active, an UIC link will
>> +        0   UFS device will stay active, UIC link will
>>              stay active
>> -        1   an UFS device will stay active, an UIC link will
>> +        1   UFS device will stay active, UIC link will
>>              hibernate
>> -        2   an UFS device will moved to sleep, an UIC link will
>> +        2   UFS device will be moved to sleep, UIC link will
>>              stay active
>> -        3   an UFS device will moved to sleep, an UIC link will
>> +        3   UFS device will be moved to sleep, UIC link will
>>              hibernate
>> -        4   an UFS device will be powered off, an UIC link will
>> +        4   UFS device will be powered off, UIC link will
>>              hibernate
>> -        5   an UFS device will be powered off, an UIC link will
>> +        5   UFS device will be powered off, UIC link will
>>              be powered off
>> +        6   UFS device will be moved to deep sleep, UIC link
>> +        will be powered off. Note, deep sleep might not be
>> +        supported in which case this value will not be accepted
> 
> Nitpicking, usually higher spm/rpm_lvl means better power saving.
> Since POWERDOWN+LINKOFF achieves the lowest power consumption, can
> we put DEEPSLEEP_LINKOFF to 5, and POWERDOWN_LINKOFF to 6?

That would break the API i.e. we shouldn't change the meaning of '5'

Also, pedantically it depends on whether regulators are provided as to
whether Deep Sleep is higher/lower than PowerDown i.e. without regulators to
switch off the device, it will remain in PowerDown mode which does not save
as much power as Deep Sleep.

> 
> Thanks,
> 
> Can Guo.
> 
>>          ==  ====================================================
>>
>>  What:        /sys/bus/platform/drivers/ufshcd/*/rpm_target_dev_state
>> @@ -954,21 +957,24 @@ Date:        September 2014
>>  Contact:    Subhash Jadavani <subhashj@codeaurora.org>
>>  Description:    This entry could be used to set or show the UFS device
>>          system power management level. The current driver
>> -        implementation supports 6 levels with next target states:
>> +        implementation supports 7 levels with next target states:
>>
>>          ==  ====================================================
>> -        0   an UFS device will stay active, an UIC link will
>> +        0   UFS device will stay active, UIC link will
>>              stay active
>> -        1   an UFS device will stay active, an UIC link will
>> +        1   UFS device will stay active, UIC link will
>>              hibernate
>> -        2   an UFS device will moved to sleep, an UIC link will
>> +        2   UFS device will be moved to sleep, UIC link will
>>              stay active
>> -        3   an UFS device will moved to sleep, an UIC link will
>> +        3   UFS device will be moved to sleep, UIC link will
>>              hibernate
>> -        4   an UFS device will be powered off, an UIC link will
>> +        4   UFS device will be powered off, UIC link will
>>              hibernate
>> -        5   an UFS device will be powered off, an UIC link will
>> +        5   UFS device will be powered off, UIC link will
>>              be powered off
>> +        6   UFS device will be moved to deep sleep, UIC link
>> +        will be powered off. Note, deep sleep might not be
>> +        supported in which case this value will not be accepted
>>          ==  ====================================================
>>
>>  What:        /sys/bus/platform/drivers/ufshcd/*/spm_target_dev_state
>> diff --git a/drivers/scsi/ufs/ufs-sysfs.c b/drivers/scsi/ufs/ufs-sysfs.c
>> index bdcd27faa054..08e72b7eef6a 100644
>> --- a/drivers/scsi/ufs/ufs-sysfs.c
>> +++ b/drivers/scsi/ufs/ufs-sysfs.c
>> @@ -28,6 +28,7 @@ static const char *ufschd_ufs_dev_pwr_mode_to_string(
>>      case UFS_ACTIVE_PWR_MODE:    return "ACTIVE";
>>      case UFS_SLEEP_PWR_MODE:    return "SLEEP";
>>      case UFS_POWERDOWN_PWR_MODE:    return "POWERDOWN";
>> +    case UFS_DEEPSLEEP_PWR_MODE:    return "DEEPSLEEP";
>>      default:            return "UNKNOWN";
>>      }
>>  }
>> @@ -38,6 +39,7 @@ static inline ssize_t ufs_sysfs_pm_lvl_store(struct
>> device *dev,
>>                           bool rpm)
>>  {
>>      struct ufs_hba *hba = dev_get_drvdata(dev);
>> +    struct ufs_dev_info *dev_info = &hba->dev_info;
>>      unsigned long flags, value;
>>
>>      if (kstrtoul(buf, 0, &value))
>> @@ -46,6 +48,11 @@ static inline ssize_t ufs_sysfs_pm_lvl_store(struct
>> device *dev,
>>      if (value >= UFS_PM_LVL_MAX)
>>          return -EINVAL;
>>
>> +    if (ufs_pm_lvl_states[value].dev_state == UFS_DEEPSLEEP_PWR_MODE &&
>> +        (!(hba->caps & UFSHCD_CAP_DEEPSLEEP) ||
>> +         !(dev_info->wspecversion >= 0x310)))
>> +        return -EINVAL;
>> +
>>      spin_lock_irqsave(hba->host->host_lock, flags);
>>      if (rpm)
>>          hba->rpm_lvl = value;
>> diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
>> index f8ab16f30fdc..d593edb48767 100644
>> --- a/drivers/scsi/ufs/ufs.h
>> +++ b/drivers/scsi/ufs/ufs.h
>> @@ -442,6 +442,7 @@ enum ufs_dev_pwr_mode {
>>      UFS_ACTIVE_PWR_MODE    = 1,
>>      UFS_SLEEP_PWR_MODE    = 2,
>>      UFS_POWERDOWN_PWR_MODE    = 3,
>> +    UFS_DEEPSLEEP_PWR_MODE    = 4,
>>  };
>>
>>  #define UFS_WB_BUF_REMAIN_PERCENT(val) ((val) / 10)
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 2309253d3101..ee083b96e405 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -163,6 +163,11 @@ struct ufs_pm_lvl_states ufs_pm_lvl_states[] = {
>>      {UFS_SLEEP_PWR_MODE, UIC_LINK_HIBERN8_STATE},
>>      {UFS_POWERDOWN_PWR_MODE, UIC_LINK_HIBERN8_STATE},
>>      {UFS_POWERDOWN_PWR_MODE, UIC_LINK_OFF_STATE},
>> +    /*
>> +     * For DeepSleep, the link is first put in hibern8 and then off.
>> +     * Leaving the link in hibern8 is not supported.
>> +     */
>> +    {UFS_DEEPSLEEP_PWR_MODE, UIC_LINK_OFF_STATE},
>>  };
>>
>>  static inline enum ufs_dev_pwr_mode
>> @@ -8297,7 +8302,8 @@ static int ufshcd_link_state_transition(struct
>> ufs_hba *hba,
>>      }
>>      /*
>>       * If autobkops is enabled, link can't be turned off because
>> -     * turning off the link would also turn off the device.
>> +     * turning off the link would also turn off the device, except in the
>> +     * case of DeepSleep where the device is expected to remain powered.
>>       */
>>      else if ((req_link_state == UIC_LINK_OFF_STATE) &&
>>           (!check_for_bkops || !hba->auto_bkops_enabled)) {
>> @@ -8307,6 +8313,9 @@ static int ufshcd_link_state_transition(struct
>> ufs_hba *hba,
>>           * put the link in low power mode is to send the DME end point
>>           * to device and then send the DME reset command to local
>>           * unipro. But putting the link in hibern8 is much faster.
>> +         *
>> +         * Note also that putting the link in Hibern8 is a requirement
>> +         * for entering DeepSleep.
>>           */
>>          ret = ufshcd_uic_hibern8_enter(hba);
>>          if (ret) {
>> @@ -8439,6 +8448,7 @@ static void ufshcd_hba_vreg_set_hpm(struct ufs_hba
>> *hba)
>>  static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>  {
>>      int ret = 0;
>> +    int check_for_bkops;
>>      enum ufs_pm_level pm_lvl;
>>      enum ufs_dev_pwr_mode req_dev_pwr_mode;
>>      enum uic_link_state req_link_state;
>> @@ -8524,7 +8534,13 @@ static int ufshcd_suspend(struct ufs_hba *hba,
>> enum ufs_pm_op pm_op)
>>      }
>>
>>      flush_work(&hba->eeh_work);
>> -    ret = ufshcd_link_state_transition(hba, req_link_state, 1);
>> +
>> +    /*
>> +     * In the case of DeepSleep, the device is expected to remain powered
>> +     * with the link off, so do not check for bkops.
>> +     */
>> +    check_for_bkops = !ufshcd_is_ufs_dev_deepsleep(hba);
>> +    ret = ufshcd_link_state_transition(hba, req_link_state,
>> check_for_bkops);
>>      if (ret)
>>          goto set_dev_active;
>>
>> @@ -8565,11 +8581,25 @@ static int ufshcd_suspend(struct ufs_hba *hba,
>> enum ufs_pm_op pm_op)
>>      if (hba->clk_scaling.is_allowed)
>>          ufshcd_resume_clkscaling(hba);
>>      ufshcd_vreg_set_hpm(hba);
>> +    /*
>> +     * Device hardware reset is required to exit DeepSleep. Also, for
>> +     * DeepSleep, the link is off so host reset and restore will be done
>> +     * further below.
>> +     */
>> +    if (ufshcd_is_ufs_dev_deepsleep(hba)) {
>> +        ufshcd_vops_device_reset(hba);
>> +        WARN_ON(!ufshcd_is_link_off(hba));
>> +    }
>>      if (ufshcd_is_link_hibern8(hba) && !ufshcd_uic_hibern8_exit(hba))
>>          ufshcd_set_link_active(hba);
>>      else if (ufshcd_is_link_off(hba))
>>          ufshcd_host_reset_and_restore(hba);
>>  set_dev_active:
>> +    /* Can also get here needing to exit DeepSleep */
>> +    if (ufshcd_is_ufs_dev_deepsleep(hba)) {
>> +        ufshcd_vops_device_reset(hba);
>> +        ufshcd_host_reset_and_restore(hba);
>> +    }
>>      if (!ufshcd_set_dev_pwr_mode(hba, UFS_ACTIVE_PWR_MODE))
>>          ufshcd_disable_auto_bkops(hba);
>>  enable_gating:
>> @@ -8631,6 +8661,9 @@ static int ufshcd_resume(struct ufs_hba *hba,
>> enum ufs_pm_op pm_op)
>>      if (ret)
>>          goto disable_vreg;
>>
>> +    /* For DeepSleep, the only supported option is to have the link off */
>> +    WARN_ON(ufshcd_is_ufs_dev_deepsleep(hba) && !ufshcd_is_link_off(hba));
>> +
>>      if (ufshcd_is_link_hibern8(hba)) {
>>          ret = ufshcd_uic_hibern8_exit(hba);
>>          if (!ret) {
>> @@ -8644,6 +8677,8 @@ static int ufshcd_resume(struct ufs_hba *hba,
>> enum ufs_pm_op pm_op)
>>          /*
>>           * A full initialization of the host and the device is
>>           * required since the link was put to off during suspend.
>> +         * Note, in the case of DeepSleep, the device will exit
>> +         * DeepSleep due to device reset.
>>           */
>>          ret = ufshcd_reset_and_restore(hba);
>>          /*
>> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
>> index 0fbb735bb70c..213be0667b59 100644
>> --- a/drivers/scsi/ufs/ufshcd.h
>> +++ b/drivers/scsi/ufs/ufshcd.h
>> @@ -114,16 +114,22 @@ enum uic_link_state {
>>      ((h)->curr_dev_pwr_mode = UFS_SLEEP_PWR_MODE)
>>  #define ufshcd_set_ufs_dev_poweroff(h) \
>>      ((h)->curr_dev_pwr_mode = UFS_POWERDOWN_PWR_MODE)
>> +#define ufshcd_set_ufs_dev_deepsleep(h) \
>> +    ((h)->curr_dev_pwr_mode = UFS_DEEPSLEEP_PWR_MODE)
>>  #define ufshcd_is_ufs_dev_active(h) \
>>      ((h)->curr_dev_pwr_mode == UFS_ACTIVE_PWR_MODE)
>>  #define ufshcd_is_ufs_dev_sleep(h) \
>>      ((h)->curr_dev_pwr_mode == UFS_SLEEP_PWR_MODE)
>>  #define ufshcd_is_ufs_dev_poweroff(h) \
>>      ((h)->curr_dev_pwr_mode == UFS_POWERDOWN_PWR_MODE)
>> +#define ufshcd_is_ufs_dev_deepsleep(h) \
>> +    ((h)->curr_dev_pwr_mode == UFS_DEEPSLEEP_PWR_MODE)
>>
>>  /*
>>   * UFS Power management levels.
>> - * Each level is in increasing order of power savings.
>> + * Each level is in increasing order of power savings, except DeepSleep
>> + * which is lower than PowerDown with power on but not PowerDown with
>> + * power off.
>>   */
>>  enum ufs_pm_level {
>>      UFS_PM_LVL_0, /* UFS_ACTIVE_PWR_MODE, UIC_LINK_ACTIVE_STATE */
>> @@ -132,6 +138,7 @@ enum ufs_pm_level {
>>      UFS_PM_LVL_3, /* UFS_SLEEP_PWR_MODE, UIC_LINK_HIBERN8_STATE */
>>      UFS_PM_LVL_4, /* UFS_POWERDOWN_PWR_MODE, UIC_LINK_HIBERN8_STATE */
>>      UFS_PM_LVL_5, /* UFS_POWERDOWN_PWR_MODE, UIC_LINK_OFF_STATE */
>> +    UFS_PM_LVL_6, /* UFS_DEEPSLEEP_PWR_MODE, UIC_LINK_OFF_STATE */
>>      UFS_PM_LVL_MAX
>>  };
>>
>> @@ -599,6 +606,14 @@ enum ufshcd_caps {
>>       * This would increase power savings.
>>       */
>>      UFSHCD_CAP_AGGR_POWER_COLLAPSE            = 1 << 9,
>> +
>> +    /*
>> +     * This capability allows the host controller driver to use DeepSleep,
>> +     * if it is supported by the UFS device. The host controller driver must
>> +     * support device hardware reset via the hba->device_reset() callback,
>> +     * in order to exit DeepSleep state.
>> +     */
>> +    UFSHCD_CAP_DEEPSLEEP                = 1 << 10,
>>  };
>>
>>  struct ufs_hba_variant_params {
>> diff --git a/include/trace/events/ufs.h b/include/trace/events/ufs.h
>> index 84841b3a7ffd..2362244c2a9e 100644
>> --- a/include/trace/events/ufs.h
>> +++ b/include/trace/events/ufs.h
>> @@ -19,7 +19,8 @@
>>  #define UFS_PWR_MODES            \
>>      EM(UFS_ACTIVE_PWR_MODE)        \
>>      EM(UFS_SLEEP_PWR_MODE)        \
>> -    EMe(UFS_POWERDOWN_PWR_MODE)
>> +    EM(UFS_POWERDOWN_PWR_MODE)    \
>> +    EMe(UFS_DEEPSLEEP_PWR_MODE)
>>
>>  #define UFSCHD_CLK_GATING_STATES    \
>>      EM(CLKS_OFF)            \