scsi: ufs: kick start clock scaling only after device detection

UFS clock scaling might start kicking in even before the device
is running at the fastest interface speed which is undesirable.
This change moves the clock scaling kick start only after the
device is detected and running at the fastest interface speed.

Change-Id: Id9af7b31eab5b67f4cf2eb38c4e90a568e7968c5
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>

drivers/scsi/ufs/ufshcd.c

@@ -372,6 +372,28 @@ static void __ufshcd_suspend_clkscaling(struct ufs_hba *hba);
 static void ufshcd_release_all(struct ufs_hba *hba);
 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_devfreq_target(struct device *dev,
+				unsigned long *freq, u32 flags);
+static int ufshcd_devfreq_get_dev_status(struct device *dev,
+		struct devfreq_dev_status *stat);
+
+#if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
+static struct devfreq_simple_ondemand_data ufshcd_ondemand_data = {
+	.upthreshold = 35,
+	.downdifferential = 30,
+	.simple_scaling = 1,
+};
+
+static void *gov_data = &ufshcd_ondemand_data;
+#else
+static void *gov_data;
+#endif
+
+static struct devfreq_dev_profile ufs_devfreq_profile = {
+	.polling_ms	= 40,
+	.target		= ufshcd_devfreq_target,
+	.get_dev_status	= ufshcd_devfreq_get_dev_status,
+};
 
 static inline bool ufshcd_valid_tag(struct ufs_hba *hba, int tag)
 {
@@ -6877,20 +6899,31 @@ static int ufshcd_probe_hba(struct ufs_hba *hba)
 		if (ufshcd_scsi_add_wlus(hba))
 			goto out;
 
-		scsi_scan_host(hba->host);
+		/* Initialize devfreq after UFS device is detected */
-		pm_runtime_put_sync(hba->dev);
-	}
-
-	/* Resume devfreq after UFS device is detected */
 		if (ufshcd_is_clkscaling_supported(hba)) {
-		memcpy(&hba->clk_scaling.saved_pwr_info.info, &hba->pwr_info,
+			memcpy(&hba->clk_scaling.saved_pwr_info.info,
-		       sizeof(struct ufs_pa_layer_attr));
+			    &hba->pwr_info, sizeof(struct ufs_pa_layer_attr));
 			hba->clk_scaling.saved_pwr_info.is_valid = true;
 			hba->clk_scaling.is_scaled_up = true;
-		ufshcd_resume_clkscaling(hba);
+			if (!hba->devfreq) {
+				hba->devfreq = devfreq_add_device(hba->dev,
+							&ufs_devfreq_profile,
+							"simple_ondemand",
+							gov_data);
+				if (IS_ERR(hba->devfreq)) {
+					ret = PTR_ERR(hba->devfreq);
+					dev_err(hba->dev, "Unable to register with devfreq %d\n",
+						ret);
+					goto out;
+				}
+			}
 			hba->clk_scaling.is_allowed = true;
 		}
 
+		scsi_scan_host(hba->host);
+		pm_runtime_put_sync(hba->dev);
+	}
+
 	if (!hba->is_init_prefetch)
 		hba->is_init_prefetch = true;
 
@@ -7700,6 +7733,7 @@ static void ufshcd_hba_exit(struct ufs_hba *hba)
 		ufshcd_variant_hba_exit(hba);
 		ufshcd_setup_vreg(hba, false);
 		if (ufshcd_is_clkscaling_supported(hba)) {
+			if (hba->devfreq)
 				ufshcd_suspend_clkscaling(hba);
 			destroy_workqueue(hba->clk_scaling.workq);
 		}
@@ -9001,23 +9035,6 @@ start_window:
 	return 0;
 }
 
-#if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
-static struct devfreq_simple_ondemand_data ufshcd_ondemand_data = {
-	.upthreshold = 35,
-	.downdifferential = 30,
-	.simple_scaling = 1,
-};
-
-static void *gov_data = &ufshcd_ondemand_data;
-#else
-static void *gov_data;
-#endif
-
-static struct devfreq_dev_profile ufs_devfreq_profile = {
-	.polling_ms	= 40,
-	.target		= ufshcd_devfreq_target,
-	.get_dev_status	= ufshcd_devfreq_get_dev_status,
-};
 static void ufshcd_clkscaling_init_sysfs(struct ufs_hba *hba)
 {
 	hba->clk_scaling.enable_attr.show = ufshcd_clkscale_enable_show;
@@ -9182,15 +9199,6 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 	if (ufshcd_is_clkscaling_supported(hba)) {
 		char wq_name[sizeof("ufs_clkscaling_00")];
 
-		hba->devfreq = devfreq_add_device(dev, &ufs_devfreq_profile,
-						   "simple_ondemand", gov_data);
-		if (IS_ERR(hba->devfreq)) {
-			dev_err(hba->dev, "Unable to register with devfreq %ld\n",
-					PTR_ERR(hba->devfreq));
-			goto out_remove_scsi_host;
-		}
-		hba->clk_scaling.is_suspended = false;
-
 		INIT_WORK(&hba->clk_scaling.suspend_work,
 			  ufshcd_clk_scaling_suspend_work);
 		INIT_WORK(&hba->clk_scaling.resume_work,
@@ -9200,8 +9208,6 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 			 host->host_no);
 		hba->clk_scaling.workq = create_singlethread_workqueue(wq_name);
 
-		/* Suspend devfreq until the UFS device is detected */
-		ufshcd_suspend_clkscaling(hba);
 		ufshcd_clkscaling_init_sysfs(hba);
 	}