Date:   Fri, 19 Feb 2021 10:18:40 -0800
From:   Asutosh Das <asutoshd@...eaurora.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     cang@...eaurora.org, martin.petersen@...cle.com,
        linux-scsi@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        stern@...land.harvard.edu, Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Kiwoong Kim <kwmad.kim@...sung.com>,
        Satya Tangirala <satyat@...gle.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v3 1/1] scsi: ufs: Enable power management for wlun

On Fri, Feb 19 2021 at 00:35 -0800, Adrian Hunter wrote:
>On 11/02/21 9:18 pm, Asutosh Das wrote:
>> During runtime-suspend of ufs host, the scsi devices are
>> already suspended and so are the queues associated with them.
>> But the ufs host sends SSU to wlun during its runtime-suspend.
>> During the process blk_queue_enter checks if the queue is not in
>> suspended state. If so, it waits for the queue to resume, and never
>> comes out of it.
>> The commit
>> (d55d15a33: scsi: block: Do not accept any requests while suspended)
>> adds the check if the queue is in suspended state in blk_queue_enter().
>>
>> Call trace:
>>  __switch_to+0x174/0x2c4
>>  __schedule+0x478/0x764
>>  schedule+0x9c/0xe0
>>  blk_queue_enter+0x158/0x228
>>  blk_mq_alloc_request+0x40/0xa4
>>  blk_get_request+0x2c/0x70
>>  __scsi_execute+0x60/0x1c4
>>  ufshcd_set_dev_pwr_mode+0x124/0x1e4
>>  ufshcd_suspend+0x208/0x83c
>>  ufshcd_runtime_suspend+0x40/0x154
>>  ufshcd_pltfrm_runtime_suspend+0x14/0x20
>>  pm_generic_runtime_suspend+0x28/0x3c
>>  __rpm_callback+0x80/0x2a4
>>  rpm_suspend+0x308/0x614
>>  rpm_idle+0x158/0x228
>>  pm_runtime_work+0x84/0xac
>>  process_one_work+0x1f0/0x470
>>  worker_thread+0x26c/0x4c8
>>  kthread+0x13c/0x320
>>  ret_from_fork+0x10/0x18
>>
>> Fix this by registering ufs device wlun as a scsi driver and
>> registering it for block runtime-pm. Also make this as a
>> supplier for all other luns. That way, this device wlun
>> suspends after all the consumers and resumes after
>> hba resumes.
>
>Sounds reasonable.  Thanks for doing this.  Some comments below.
>
>>
>> Co-developed-by: Can Guo <cang@...eaurora.org>
>> Signed-off-by: Can Guo <cang@...eaurora.org>
>> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
>> ---
>>  drivers/scsi/ufs/ufshcd.c  | 415 +++++++++++++++++++++++++++++++++++++--------
>>  drivers/scsi/ufs/ufshcd.h  |   4 +
>>  include/trace/events/ufs.h |  20 +++
>>  3 files changed, 364 insertions(+), 75 deletions(-)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 45624c7..e92dbde 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -16,6 +16,7 @@
>>  #include <linux/bitfield.h>
>>  #include <linux/blk-pm.h>
>>  #include <linux/blkdev.h>
>> +#include <scsi/scsi_driver.h>
>>  #include "ufshcd.h"
>>  #include "ufs_quirks.h"
>>  #include "unipro.h"
>> @@ -251,6 +252,13 @@ static int ufshcd_wb_toggle_flush_during_h8(struct ufs_hba *hba, bool set);
>>  static inline int ufshcd_wb_toggle_flush(struct ufs_hba *hba, bool enable);
>>  static void ufshcd_hba_vreg_set_lpm(struct ufs_hba *hba);
>>  static void ufshcd_hba_vreg_set_hpm(struct ufs_hba *hba);
>> +static int __ufshcd_wl_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op);
>> +static int __ufshcd_wl_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op);
>> +static int ufshcd_wl_runtime_suspend(struct device *dev);
>> +static int ufshcd_wl_runtime_resume(struct device *dev);
>> +static int ufshcd_wl_suspend(struct device *dev);
>> +static int ufshcd_wl_resume(struct device *dev);
>> +static void ufshcd_wl_shutdown(struct device *dev);
>
>Please try to reduce the number of forward declarations.
>
Done, I think I can reduce a couple of these.

>>
>>  static inline bool ufshcd_valid_tag(struct ufs_hba *hba, int tag)
>>  {
>> @@ -2572,6 +2580,17 @@ static inline u16 ufshcd_upiu_wlun_to_scsi_wlun(u8 upiu_wlun_id)
>>  	return (upiu_wlun_id & ~UFS_UPIU_WLUN_ID) | SCSI_W_LUN_BASE;
>>  }
>>
>> +static inline bool is_rpmb_wlun(struct scsi_device *sdev)
>> +{
>> +	return (sdev->lun == ufshcd_upiu_wlun_to_scsi_wlun(UFS_UPIU_RPMB_WLUN));
>> +}
>> +
>> +static inline bool is_device_wlun(struct scsi_device *sdev)
>> +{
>> +	return (sdev->lun ==
>> +		ufshcd_upiu_wlun_to_scsi_wlun(UFS_UPIU_UFS_DEVICE_WLUN));
>> +}
>> +
>>  static void ufshcd_init_lrb(struct ufs_hba *hba, struct ufshcd_lrb *lrb, int i)
>>  {
>>  	struct utp_transfer_cmd_desc *cmd_descp = hba->ucdl_base_addr;
>> @@ -4808,6 +4827,43 @@ static inline void ufshcd_get_lu_power_on_wp_status(struct ufs_hba *hba,
>>  }
>>
>>  /**
>> + * ufshcd_setup_links - associate link b/w device wlun and other luns
>> + * @sdev: pointer to SCSI device
>> + * @hba: pointer to ufs hba
>> + *
>> + * Returns void
>> + */
>> +static void ufshcd_setup_links(struct ufs_hba *hba, struct scsi_device *sdev)
>> +{
>> +	struct device_link *link;
>> +
>> +	/*
>> +	 * device wlun is the supplier & rest of the luns are consumers
>> +	 * This ensures that device wlun suspends after all other luns.
>> +	 */
>> +	if (hba->sdev_ufs_device) {
>> +		link = device_link_add(&sdev->sdev_gendev,
>> +				       &hba->sdev_ufs_device->sdev_gendev,
>> +				       DL_FLAG_PM_RUNTIME);
>> +		if (!link) {
>> +			dev_err(&sdev->sdev_gendev, "Failed establishing link - %s\n",
>> +				dev_name(&hba->sdev_ufs_device->sdev_gendev));
>> +			return;
>> +		}
>> +		hba->luns_avail--;
>> +		/* Ignore REPORT_LUN wlun probing */
>> +		if (hba->luns_avail != 1)
>> +			return;
>> +
>> +		pm_runtime_put_noidle(&hba->sdev_ufs_device->sdev_gendev);
>> +		pm_runtime_mark_last_busy(&hba->sdev_ufs_device->sdev_gendev);
>> +	} else {
>> +		/* device wlun is probed */
>> +		hba->luns_avail--;
>> +	}
>> +}
>> +
>> +/**
>>   * ufshcd_slave_alloc - handle initial SCSI device configurations
>>   * @sdev: pointer to SCSI device
>>   *
>> @@ -4838,6 +4894,8 @@ static int ufshcd_slave_alloc(struct scsi_device *sdev)
>>
>>  	ufshcd_get_lu_power_on_wp_status(hba, sdev);
>>
>> +	ufshcd_setup_links(hba, sdev);
>> +
>>  	return 0;
>>  }
>>
>> @@ -5589,8 +5647,8 @@ static void ufshcd_rpm_dev_flush_recheck_work(struct work_struct *work)
>>  	 * after a certain delay to recheck the threshold by next runtime
>>  	 * suspend.
>>  	 */
>> -	pm_runtime_get_sync(hba->dev);
>> -	pm_runtime_put_sync(hba->dev);
>> +	scsi_autopm_get_device(hba->sdev_ufs_device);
>> +	scsi_autopm_put_device(hba->sdev_ufs_device);
>>  }
>>
>>  /**
>> @@ -7254,6 +7312,14 @@ static int ufshcd_scsi_add_wlus(struct ufs_hba *hba)
>>  		goto out;
>>  	}
>>  	ufshcd_blk_pm_runtime_init(hba->sdev_ufs_device);
>> +	/*
>> +	 * A pm_runtime_put_sync is invoked when this device enables blk_pm_runtime
>> +	 * & would suspend the device-wlun upon timer expiry.
>> +	 * But suspending device wlun _may_ put the ufs device in the pre-defined
>> +	 * low power mode (SSU <rpm_lvl>). Probing of other luns may fail then.
>> +	 * Don't allow this suspend until all the luns have been probed.
>> +	 */
>> +	pm_runtime_get_noresume(&hba->sdev_ufs_device->sdev_gendev);
>>  	scsi_device_put(hba->sdev_ufs_device);
>>
>>  	hba->sdev_rpmb = __scsi_add_device(hba->host, 0, 0,
>> @@ -7417,6 +7483,9 @@ static int ufs_get_device_desc(struct ufs_hba *hba)
>>  		goto out;
>>  	}
>>
>> +	hba->luns_avail = desc_buf[DEVICE_DESC_PARAM_NUM_LU] +
>> +		desc_buf[DEVICE_DESC_PARAM_NUM_WLU];
>> +
>>  	ufs_fixup_device_setup(hba);
>>
>>  	ufshcd_wb_probe(hba, desc_buf);
>> @@ -7747,6 +7816,54 @@ static int ufshcd_device_params_init(struct ufs_hba *hba)
>>  	return ret;
>>  }
>>
>> +static int ufshcd_wl_probe(struct device *dev)
>> +{
>> +	struct scsi_device *sdev = to_scsi_device(dev);
>> +
>> +	/*
>> +	 * Use this driver for both device wlun and rpmb lun
>> +	 * It's used to send uac to rpmb wlun and ssu to device wlun
>> +	 */
>> +	if (sdev && (is_rpmb_wlun(sdev) || is_device_wlun(sdev)))
>> +		return 0;
>> +	return -ENODEV;
>> +}
>> +
>> +static int ufshcd_wl_remove(struct device *dev)
>> +{
>> +	struct scsi_device *sdev = to_scsi_device(dev);
>> +
>> +	scsi_remove_device(sdev);
>> +	return 0;
>> +}
>> +
>> +static const struct dev_pm_ops ufshcd_wl_pm_ops = {
>> +	SET_RUNTIME_PM_OPS(ufshcd_wl_runtime_suspend, ufshcd_wl_runtime_resume, NULL)
>> +	SET_SYSTEM_SLEEP_PM_OPS(ufshcd_wl_suspend, ufshcd_wl_resume)
>> +};
>> +
>> +/**
>> + * ufs_wlun - describes 2 wluns:
>> + * ufs-device wlun - used to send pm commands
>> + * and rpmb wlun - for rpmb commands
>
>There seems to be no common code for those 2, so could they be separate drivers?
>

I suppose so. The reason I bundled the 2 together is the rpmb driver was only
for clearing uac. The rest would be mostly empty functions.
I'm fine to separate it out though. Let me code it up and see if it makes sense.

>> + * All luns including rpmb are consumers of ufs-device wlun.
>> + *
>> + * Currently, no sd driver is present for wluns.
>> + * Hence the no specific pm operations are performed.
>> + * With ufs design, SSU should be sent to ufs-device wlun.
>> + * Hence register a scsi driver for ufs wluns only.
>> + */
>> +static struct scsi_driver ufs_wlun = {
>> +	.gendrv = {
>> +		.name = "ufs_device_wlun",
>> +		.owner = THIS_MODULE,
>> +		.probe = ufshcd_wl_probe,
>> +		.remove = ufshcd_wl_remove,
>> +		.pm = &ufshcd_wl_pm_ops,
>> +		.shutdown = ufshcd_wl_shutdown,
>> +	},
>> +};
>> +
>>  /**
>>   * ufshcd_add_lus - probe and add UFS logical units
>>   * @hba: per-adapter instance
>> @@ -7755,6 +7872,12 @@ static int ufshcd_add_lus(struct ufs_hba *hba)
>>  {
>>  	int ret;
>>
>> +	ret = scsi_register_driver(&ufs_wlun.gendrv);
>> +	if (ret) {
>> +		dev_err(hba->dev, "Register device wlun driver failed: %d\n",
>> +			ret);
>> +		return ret;
>> +	}
>>  	/* Add required well known logical units to scsi mid layer */
>>  	ret = ufshcd_scsi_add_wlus(hba);
>>  	if (ret)
>> @@ -7964,6 +8087,7 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
>>  		pm_runtime_put_sync(hba->dev);
>>  		ufshcd_hba_exit(hba);
>>  	}
>> +	hba->init_done = true;
>>  }
>>
>>  static const struct attribute_group *ufshcd_driver_groups[] = {
>> @@ -8475,7 +8599,8 @@ static int ufshcd_set_dev_pwr_mode(struct ufs_hba *hba,
>>  	 * handling context.
>>  	 */
>>  	hba->host->eh_noresume = 1;
>> -	ufshcd_clear_ua_wluns(hba);
>> +	if (hba->wlun_dev_clr_ua)
>> +		ufshcd_clear_ua_wlun(hba, UFS_UPIU_UFS_DEVICE_WLUN);
>>
>>  	cmd[4] = pwr_mode << 4;
>>
>> @@ -8650,26 +8775,9 @@ static void ufshcd_hba_vreg_set_hpm(struct ufs_hba *hba)
>>  		ufshcd_setup_hba_vreg(hba, true);
>>  }
>>
>> -/**
>> - * ufshcd_suspend - helper function for suspend operations
>> - * @hba: per adapter instance
>> - * @pm_op: desired low power operation type
>> - *
>> - * This function will try to put the UFS device and link into low power
>> - * mode based on the "rpm_lvl" (Runtime PM level) or "spm_lvl"
>> - * (System PM level).
>> - *
>> - * If this function is called during shutdown, it will make sure that
>> - * both UFS device and UFS link is powered off.
>> - *
>> - * NOTE: UFS device & link must be active before we enter in this function.
>> - *
>> - * Returns 0 for success and non-zero for failure
>> - */
>> -static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>> +static int __ufshcd_wl_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;
>> @@ -8690,24 +8798,23 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>  	 * just gate the clocks.
>>  	 */
>>  	ufshcd_hold(hba, false);
>> -	hba->clk_gating.is_suspended = true;
>>
>>  	if (ufshcd_is_clkscaling_supported(hba))
>>  		ufshcd_clk_scaling_suspend(hba, true);
>>
>>  	if (req_dev_pwr_mode == UFS_ACTIVE_PWR_MODE &&
>>  			req_link_state == UIC_LINK_ACTIVE_STATE) {
>> -		goto disable_clks;
>> +		goto enable_scaling;
>>  	}
>>
>>  	if ((req_dev_pwr_mode == hba->curr_dev_pwr_mode) &&
>>  	    (req_link_state == hba->uic_link_state))
>> -		goto enable_gating;
>> +		goto enable_scaling;
>>
>>  	/* UFS device & link must be active before we enter in this function */
>>  	if (!ufshcd_is_ufs_dev_active(hba) || !ufshcd_is_link_active(hba)) {
>>  		ret = -EINVAL;
>> -		goto enable_gating;
>> +		goto enable_scaling;
>>  	}
>>
>>  	if (ufshcd_is_runtime_pm(pm_op)) {
>> @@ -8719,7 +8826,7 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>  			 */
>>  			ret = ufshcd_urgent_bkops(hba);
>>  			if (ret)
>> -				goto enable_gating;
>> +				goto enable_scaling;
>>  		} else {
>>  			/* make sure that auto bkops is disabled */
>>  			ufshcd_disable_auto_bkops(hba);
>> @@ -8746,10 +8853,214 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>
>>  		if (!hba->dev_info.b_rpm_dev_flush_capable) {
>>  			ret = ufshcd_set_dev_pwr_mode(hba, req_dev_pwr_mode);
>> -			if (ret)
>> -				goto enable_gating;
>> +			if (!ret)
>> +				goto out;
>>  		}
>>  	}
>> +enable_scaling:
>> +	if (ufshcd_is_clkscaling_supported(hba))
>> +		ufshcd_clk_scaling_suspend(hba, false);
>> +
>> +	hba->dev_info.b_rpm_dev_flush_capable = false;
>> +out:
>> +	if (hba->dev_info.b_rpm_dev_flush_capable) {
>> +		schedule_delayed_work(&hba->rpm_dev_flush_recheck_work,
>> +			msecs_to_jiffies(RPM_DEV_FLUSH_RECHECK_WORK_DELAY_MS));
>> +	}
>> +	if (ret)
>> +		ufshcd_update_evt_hist(hba, UFS_EVT_WL_SUSP_ERR, (u32)ret);
>> +	ufshcd_release(hba);
>> +	return ret;
>> +}
>> +
>> +static int __ufshcd_wl_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>> +{
>> +	int ret = 0;
>> +	enum uic_link_state old_link_state;
>> +
>> +	if (!hba->init_done)
>> +		return 0;
>> +
>> +	old_link_state = hba->uic_link_state;
>> +	ufshcd_hold(hba, false);
>> +	if (!ufshcd_is_ufs_dev_active(hba)) {
>
>You cannot assume the UFS device is not in DeepSleep here.
>i.e. the host controller may not have been suspended and resumed since the
>UFS device entered DeepSleep.
>

Good point. Let me check how to fix this.

>> +		ret = ufshcd_set_dev_pwr_mode(hba, UFS_ACTIVE_PWR_MODE);
>> +		if (ret)
>> +			goto out;
>> +	}
>> +
>> +	if (ufshcd_keep_autobkops_enabled_except_suspend(hba))
>> +		ufshcd_enable_auto_bkops(hba);
>> +	else
>> +		/*
>> +		 * If BKOPs operations are urgently needed at this moment then
>> +		 * keep auto-bkops enabled or else disable it.
>> +		 */
>> +		ufshcd_urgent_bkops(hba);
>> +
>> +	if (hba->clk_scaling.is_allowed)
>> +		ufshcd_resume_clkscaling(hba);
>> +
>> +	if (hba->dev_info.b_rpm_dev_flush_capable) {
>> +		hba->dev_info.b_rpm_dev_flush_capable = false;
>> +		cancel_delayed_work(&hba->rpm_dev_flush_recheck_work);
>> +	}
>> +
>> +out:
>> +	hba->clk_gating.is_suspended = false;
>> +	if (ret)
>> +		ufshcd_update_evt_hist(hba, UFS_EVT_WL_RES_ERR, (u32)ret);
>> +	ufshcd_release(hba);
>> +	return ret;
>> +}
>> +
>> +static int ufshcd_wl_runtime_suspend(struct device *dev)
>> +{
>> +	struct scsi_device *sdev = to_scsi_device(dev);
>> +	struct ufs_hba *hba;
>> +	int ret;
>> +	ktime_t start = ktime_get();
>> +
>> +	hba = shost_priv(sdev->host);
>> +	if (is_rpmb_wlun(sdev)) {
>> +		if (hba->sdev_rpmb)
>> +			return ufshcd_clear_ua_wlun(hba, UFS_UPIU_RPMB_WLUN);
>> +		return 0;
>> +	}
>> +
>> +	ret = __ufshcd_wl_suspend(hba, UFS_RUNTIME_PM);
>> +	if (ret)
>> +		dev_err(&sdev->sdev_gendev, "%s failed: %d\n", __func__, ret);
>> +
>> +	trace_ufshcd_wl_runtime_suspend(dev_name(dev), ret,
>> +		ktime_to_us(ktime_sub(ktime_get(), start)),
>> +		hba->curr_dev_pwr_mode, hba->uic_link_state);
>> +
>> +	return ret;
>> +}
>> +
>> +static int ufshcd_wl_runtime_resume(struct device *dev)
>> +{
>> +	struct scsi_device *sdev = to_scsi_device(dev);
>> +	struct ufs_hba *hba;
>> +	int ret;
>> +	ktime_t start = ktime_get();
>> +
>> +	hba = shost_priv(sdev->host);
>> +
>> +	if (is_rpmb_wlun(sdev))
>> +		return 0;
>> +	ret = __ufshcd_wl_resume(hba, UFS_RUNTIME_PM);
>> +	if (ret)
>> +		dev_err(&sdev->sdev_gendev, "%s failed: %d\n", __func__, ret);
>> +
>> +	trace_ufshcd_wl_runtime_resume(dev_name(dev), ret,
>> +		ktime_to_us(ktime_sub(ktime_get(), start)),
>> +		hba->curr_dev_pwr_mode, hba->uic_link_state);
>> +
>> +	return ret;
>> +}
>> +
>> +static int ufshcd_wl_suspend(struct device *dev)
>> +{
>> +	struct scsi_device *sdev = to_scsi_device(dev);
>> +	struct ufs_hba *hba;
>> +	int ret;
>> +	ktime_t start = ktime_get();
>> +
>> +	if (is_rpmb_wlun(sdev))
>> +		return 0;
>> +	hba = shost_priv(sdev->host);
>> +	ret = __ufshcd_wl_suspend(hba, UFS_SYSTEM_PM);
>> +	if (ret)
>> +		dev_err(&sdev->sdev_gendev, "%s failed: %d\n", __func__,  ret);
>> +
>> +	trace_ufshcd_wl_suspend(dev_name(dev), ret,
>> +		ktime_to_us(ktime_sub(ktime_get(), start)),
>> +		hba->curr_dev_pwr_mode, hba->uic_link_state);
>> +
>> +	return ret;
>> +
>> +}
>> +
>> +static int ufshcd_wl_resume(struct device *dev)
>> +{
>> +	struct scsi_device *sdev = to_scsi_device(dev);
>> +	struct ufs_hba *hba;
>> +	int ret;
>> +	ktime_t start = ktime_get();
>> +
>> +	if (pm_runtime_suspended(dev) || is_rpmb_wlun(sdev))
>> +		return 0;
>> +	hba = shost_priv(sdev->host);
>> +
>> +	ret = __ufshcd_wl_resume(hba, UFS_SYSTEM_PM);
>> +	if (ret)
>> +		dev_err(&sdev->sdev_gendev, "%s failed: %d\n", __func__, ret);
>> +
>> +	trace_ufshcd_wl_resume(dev_name(dev), ret,
>> +		ktime_to_us(ktime_sub(ktime_get(), start)),
>> +		hba->curr_dev_pwr_mode, hba->uic_link_state);
>> +
>> +	return ret;
>> +}
>> +
>> +static void ufshcd_wl_shutdown(struct device *dev)
>> +{
>> +	struct scsi_device *sdev = to_scsi_device(dev);
>> +	struct ufs_hba *hba;
>> +
>> +	if (is_rpmb_wlun(sdev))
>> +		return;
>> +	hba = shost_priv(sdev->host);
>> +	scsi_device_quiesce(sdev);
>> +	shost_for_each_device(sdev, hba->host) {
>> +		if (sdev == hba->sdev_ufs_device)
>> +			continue;
>> +		scsi_remove_device(sdev);
>> +	}
>> +	__ufshcd_wl_suspend(hba, UFS_SHUTDOWN_PM);
>> +}
>> +
>> +/**
>> + * ufshcd_suspend - helper function for suspend operations
>> + * @hba: per adapter instance
>> + * @pm_op: desired low power operation type
>> + *
>> + * This function will try to put the UFS link into low power
>> + * mode based on the "rpm_lvl" (Runtime PM level) or "spm_lvl"
>> + * (System PM level).
>> + *
>> + * If this function is called during shutdown, it will make sure that
>> + * link is powered off.
>> + *
>> + * Returns 0 for success and non-zero for failure
>> + */
>> +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;
>> +
>> +	hba->pm_op_in_progress = 1;
>> +	if (!ufshcd_is_shutdown_pm(pm_op)) {
>> +		pm_lvl = ufshcd_is_runtime_pm(pm_op) ?
>> +			 hba->rpm_lvl : hba->spm_lvl;
>> +		req_dev_pwr_mode = ufs_get_pm_lvl_to_dev_pwr_mode(pm_lvl);
>> +		req_link_state = ufs_get_pm_lvl_to_link_pwr_state(pm_lvl);
>> +	} else {
>> +		req_dev_pwr_mode = UFS_POWERDOWN_PWR_MODE;
>> +		req_link_state = UIC_LINK_OFF_STATE;
>> +	}
>> +
>> +	/*
>> +	 * If we can't transition into any of the low power modes
>> +	 * just gate the clocks.
>> +	 */
>> +	ufshcd_hold(hba, false);
>> +	hba->clk_gating.is_suspended = true;
>>
>>  	/*
>>  	 * In the case of DeepSleep, the device is expected to remain powered
>> @@ -8758,9 +9069,8 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>  	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;
>> +		goto enable_gating;
>>
>> -disable_clks:
>>  	/*
>>  	 * Call vendor specific suspend callback. As these callbacks may access
>>  	 * vendor specific host controller register space call them before the
>> @@ -8790,7 +9100,6 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>  	goto out;
>>
>>  set_link_active:
>> -	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
>> @@ -8804,28 +9113,15 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>  		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_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:
>> -	if (ufshcd_is_clkscaling_supported(hba))
>> -		ufshcd_clk_scaling_suspend(hba, false);
>> -
>>  	hba->clk_gating.is_suspended = false;
>> -	hba->dev_info.b_rpm_dev_flush_capable = false;
>> -	ufshcd_clear_ua_wluns(hba);
>>  	ufshcd_release(hba);
>>  out:
>> -	if (hba->dev_info.b_rpm_dev_flush_capable) {
>> -		schedule_delayed_work(&hba->rpm_dev_flush_recheck_work,
>> -			msecs_to_jiffies(RPM_DEV_FLUSH_RECHECK_WORK_DELAY_MS));
>> -	}
>> -
>>  	hba->pm_op_in_progress = 0;
>>
>>  	if (ret)
>> @@ -8846,10 +9142,8 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>  static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>  {
>>  	int ret;
>> -	enum uic_link_state old_link_state;
>>
>>  	hba->pm_op_in_progress = 1;
>> -	old_link_state = hba->uic_link_state;
>>
>>  	ufshcd_hba_vreg_set_hpm(hba);
>>  	ret = ufshcd_vreg_set_hpm(hba);
>> @@ -8901,43 +9195,14 @@ static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>>  			goto vendor_suspend;
>>  	}
>>
>> -	if (!ufshcd_is_ufs_dev_active(hba)) {
>> -		ret = ufshcd_set_dev_pwr_mode(hba, UFS_ACTIVE_PWR_MODE);
>> -		if (ret)
>> -			goto set_old_link_state;
>> -	}
>> -
>> -	if (ufshcd_keep_autobkops_enabled_except_suspend(hba))
>> -		ufshcd_enable_auto_bkops(hba);
>> -	else
>> -		/*
>> -		 * If BKOPs operations are urgently needed at this moment then
>> -		 * keep auto-bkops enabled or else disable it.
>> -		 */
>> -		ufshcd_urgent_bkops(hba);
>> -
>> -	hba->clk_gating.is_suspended = false;
>> -
>> -	if (ufshcd_is_clkscaling_supported(hba))
>> -		ufshcd_clk_scaling_suspend(hba, false);
>> -
>>  	/* Enable Auto-Hibernate if configured */
>>  	ufshcd_auto_hibern8_enable(hba);
>>
>> -	if (hba->dev_info.b_rpm_dev_flush_capable) {
>> -		hba->dev_info.b_rpm_dev_flush_capable = false;
>> -		cancel_delayed_work(&hba->rpm_dev_flush_recheck_work);
>> -	}
>> -
>> -	ufshcd_clear_ua_wluns(hba);
>> -
>>  	/* Schedule clock gating in case of no access to UFS device yet */
>>  	ufshcd_release(hba);
>>
>>  	goto out;
>>
>> -set_old_link_state:
>> -	ufshcd_link_state_transition(hba, old_link_state, 0);
>>  vendor_suspend:
>>  	ufshcd_vops_suspend(hba, pm_op);
>>  disable_irq_and_vops_clks:
>> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
>> index ee61f82..7662387 100644
>> --- a/drivers/scsi/ufs/ufshcd.h
>> +++ b/drivers/scsi/ufs/ufshcd.h
>> @@ -72,6 +72,8 @@ enum ufs_event_type {
>>  	UFS_EVT_LINK_STARTUP_FAIL,
>>  	UFS_EVT_RESUME_ERR,
>>  	UFS_EVT_SUSPEND_ERR,
>> +	UFS_EVT_WL_SUSP_ERR,
>> +	UFS_EVT_WL_RES_ERR,
>>
>>  	/* abnormal events */
>>  	UFS_EVT_DEV_RESET,
>> @@ -841,6 +843,8 @@ struct ufs_hba {
>>  #ifdef CONFIG_DEBUG_FS
>>  	struct dentry *debugfs_root;
>>  #endif
>> +	bool init_done;
>> +	u32 luns_avail;
>>  };
>>
>>  /* Returns true if clocks can be gated. Otherwise false */
>> diff --git a/include/trace/events/ufs.h b/include/trace/events/ufs.h
>> index e151477..d9d233b 100644
>> --- a/include/trace/events/ufs.h
>> +++ b/include/trace/events/ufs.h
>> @@ -246,6 +246,26 @@ DEFINE_EVENT(ufshcd_template, ufshcd_init,
>>  		      int dev_state, int link_state),
>>  	     TP_ARGS(dev_name, err, usecs, dev_state, link_state));
>>
>> +DEFINE_EVENT(ufshcd_template, ufshcd_wl_suspend,
>> +	     TP_PROTO(const char *dev_name, int err, s64 usecs,
>> +		      int dev_state, int link_state),
>> +	     TP_ARGS(dev_name, err, usecs, dev_state, link_state));
>> +
>> +DEFINE_EVENT(ufshcd_template, ufshcd_wl_resume,
>> +	     TP_PROTO(const char *dev_name, int err, s64 usecs,
>> +		      int dev_state, int link_state),
>> +	     TP_ARGS(dev_name, err, usecs, dev_state, link_state));
>> +
>> +DEFINE_EVENT(ufshcd_template, ufshcd_wl_runtime_suspend,
>> +	     TP_PROTO(const char *dev_name, int err, s64 usecs,
>> +		      int dev_state, int link_state),
>> +	     TP_ARGS(dev_name, err, usecs, dev_state, link_state));
>> +
>> +DEFINE_EVENT(ufshcd_template, ufshcd_wl_runtime_resume,
>> +	     TP_PROTO(const char *dev_name, int err, s64 usecs,
>> +		      int dev_state, int link_state),
>> +	     TP_ARGS(dev_name, err, usecs, dev_state, link_state));
>> +
>>  TRACE_EVENT(ufshcd_command,
>>  	TP_PROTO(const char *dev_name, enum ufs_trace_str_t str_t,
>>  		 unsigned int tag, u32 doorbell, int transfer_len, u32 intr,
>>
>

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