[PATCH v3 5/5] scsi: ufs: Fix possible VCC power drain during runtime suspend

[Stanley Chu]

The commit "scsi: ufs: Fix WriteBooster flush during runtime
suspend" promises essential resource, i.e., for UFS devices doing
WriteBooster buffer flush and Auto BKOPs. However if device
finishes its job but not resumed for a very long time, system
will have unnecessary power drain because VCC is still supplied.

To fix this, a method to recheck the threshold of keeping VCC
supply is required. However, the threshold recheck needs to
re-activate the link because the decision depends on the device
status.

Introduce a delayed work to force runtime resume after a certain
delay during runtime suspend. This makes threshold recheck simpler
which will be done in the next runtime-suspend.

Signed-off-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
---
 drivers/scsi/ufs/ufs.h    |  1 +
 drivers/scsi/ufs/ufshcd.c | 43 ++++++++++++++++++++++++++++++++++-----
 drivers/scsi/ufs/ufshcd.h |  1 +
 3 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
index db07eedfed96..c70845d41449 100644
--- a/drivers/scsi/ufs/ufs.h
+++ b/drivers/scsi/ufs/ufs.h
@@ -574,6 +574,7 @@ struct ufs_dev_info {
 	u32 d_ext_ufs_feature_sup;
 	u8 b_wb_buffer_type;
 	u32 d_wb_alloc_units;
+	bool b_rpm_dev_flush_capable;
 	u8 b_presrv_uspc_en;
 };
 
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index f4f2c7b5ab0a..a137553f9b41 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -94,6 +94,9 @@
 /* default delay of autosuspend: 2000 ms */
 #define RPM_AUTOSUSPEND_DELAY_MS 2000
 
+/* Default delay of RPM device flush delayed work */
+#define RPM_DEV_FLUSH_RECHECK_WORK_DELAY_MS 5000
+
 /* Default value of wait time before gating device ref clock */
 #define UFSHCD_REF_CLK_GATING_WAIT_US 0xFF /* microsecs */
 
@@ -5310,7 +5313,7 @@ static bool ufshcd_wb_presrv_usrspc_keep_vcc_on(struct ufs_hba *hba,
 	return false;
 }
 
-static bool ufshcd_wb_keep_vcc_on(struct ufs_hba *hba)
+static bool ufshcd_wb_need_flush(struct ufs_hba *hba)
 {
 	int ret;
 	u32 avail_buf;
@@ -5348,6 +5351,21 @@ static bool ufshcd_wb_keep_vcc_on(struct ufs_hba *hba)
 	return ufshcd_wb_presrv_usrspc_keep_vcc_on(hba, avail_buf);
 }
 
+static void ufshcd_rpm_dev_flush_recheck_work(struct work_struct *work)
+{
+	struct ufs_hba *hba = container_of(to_delayed_work(work),
+					   struct ufs_hba,
+					   rpm_dev_flush_recheck_work);
+	/*
+	 * To prevent unnecessary VCC power drain after device finishes
+	 * WriteBooster buffer flush or Auto BKOPs, force runtime resume
+	 * after a certain delay to recheck the threshold by next runtime
+	 * supsend.
+	 */
+	pm_runtime_get_sync(hba->dev);
+	pm_runtime_put_sync(hba->dev);
+}
+
 /**
  * ufshcd_exception_event_handler - handle exceptions raised by device
  * @work: pointer to work data
@@ -8164,7 +8182,6 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	enum ufs_pm_level pm_lvl;
 	enum ufs_dev_pwr_mode req_dev_pwr_mode;
 	enum uic_link_state req_link_state;
-	bool keep_curr_dev_pwr_mode = false;
 
 	hba->pm_op_in_progress = 1;
 	if (!ufshcd_is_shutdown_pm(pm_op)) {
@@ -8224,11 +8241,12 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 		 * Hibern8, keep device power mode as "active power mode"
 		 * and VCC supply.
 		 */
-		keep_curr_dev_pwr_mode = hba->auto_bkops_enabled ||
+		hba->dev_info.b_rpm_dev_flush_capable =
+			hba->auto_bkops_enabled ||
 			(((req_link_state == UIC_LINK_HIBERN8_STATE) ||
 			((req_link_state == UIC_LINK_ACTIVE_STATE) &&
 			ufshcd_is_auto_hibern8_enabled(hba))) &&
-			ufshcd_wb_keep_vcc_on(hba));
+			ufshcd_wb_need_flush(hba));
 	}
 
 	if (req_dev_pwr_mode != hba->curr_dev_pwr_mode) {
@@ -8238,7 +8256,7 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 			ufshcd_disable_auto_bkops(hba);
 		}
 
-		if (!keep_curr_dev_pwr_mode) {
+		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;
@@ -8295,9 +8313,16 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	if (hba->clk_scaling.is_allowed)
 		ufshcd_resume_clkscaling(hba);
 	hba->clk_gating.is_suspended = false;
+	hba->dev_info.b_rpm_dev_flush_capable = false;
 	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)
 		ufshcd_update_reg_hist(&hba->ufs_stats.suspend_err, (u32)ret);
 	return ret;
@@ -8386,6 +8411,11 @@ static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	/* 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);
+	}
+
 	/* Schedule clock gating in case of no access to UFS device yet */
 	ufshcd_release(hba);
 
@@ -8859,6 +8889,9 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 						UFS_SLEEP_PWR_MODE,
 						UIC_LINK_HIBERN8_STATE);
 
+	INIT_DELAYED_WORK(&hba->rpm_dev_flush_recheck_work,
+			  ufshcd_rpm_dev_flush_recheck_work);
+
 	/* Set the default auto-hiberate idle timer value to 150 ms */
 	if (ufshcd_is_auto_hibern8_supported(hba) && !hba->ahit) {
 		hba->ahit = FIELD_PREP(UFSHCI_AHIBERN8_TIMER_MASK, 150) |
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 8db7a6101892..9acd437037e8 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -745,6 +745,7 @@ struct ufs_hba {
 	struct request_queue	*bsg_queue;
 	bool wb_buf_flush_enabled;
 	bool wb_enabled;
+	struct delayed_work rpm_dev_flush_recheck_work;
 };
 
 /* Returns true if clocks can be gated. Otherwise false */
-- 
2.18.0