linux-scsi.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Can Guo <cang@codeaurora.org>
To: asutoshd@codeaurora.org, nguyenb@codeaurora.org,
	hongwus@codeaurora.org, rnayak@codeaurora.org,
	linux-scsi@vger.kernel.org, kernel-team@android.com,
	saravanak@google.com, salyzyn@google.com, cang@codeaurora.org
Cc: Alim Akhtar <alim.akhtar@samsung.com>,
	Avri Altman <avri.altman@wdc.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Stanley Chu <stanley.chu@mediatek.com>,
	Bean Huo <beanhuo@micron.com>,
	Bart Van Assche <bvanassche@acm.org>,
	Satya Tangirala <satyat@google.com>,
	linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v4 1/3] scsi: ufs: Protect some contexts from unexpected clock scaling
Date: Sun, 13 Dec 2020 08:31:42 -0800	[thread overview]
Message-ID: <1607877104-8916-2-git-send-email-cang@codeaurora.org> (raw)
In-Reply-To: <1607877104-8916-1-git-send-email-cang@codeaurora.org>

In contexts like suspend, shutdown and error handling, we need to suspend
devfreq to make sure these contexts won't be disturbed by clock scaling.
However, suspending devfreq is not enough since users can still trigger a
clock scaling by manipulating the sysfs node clkscale_enable and devfreq
sysfs nodes like min/max_freq and governor. Add one more flag in struct
clk_scaling such that these contexts can prevent clock scaling from being
invoked through above sysfs nodes.

Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 83 +++++++++++++++++++++++++++++++----------------
 drivers/scsi/ufs/ufshcd.h |  2 ++
 2 files changed, 57 insertions(+), 28 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 0c148fc..4ccdd2b 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1147,12 +1147,22 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba)
 	 */
 	ufshcd_scsi_block_requests(hba);
 	down_write(&hba->clk_scaling_lock);
-	if (ufshcd_wait_for_doorbell_clr(hba, DOORBELL_CLR_TOUT_US)) {
+
+	if (!hba->clk_scaling.is_allowed)
+		ret = -EAGAIN;
+	else if (ufshcd_wait_for_doorbell_clr(hba, DOORBELL_CLR_TOUT_US))
 		ret = -EBUSY;
+
+	if (ret) {
 		up_write(&hba->clk_scaling_lock);
 		ufshcd_scsi_unblock_requests(hba);
+		goto out;
 	}
 
+	/* let's not get into low power until clock scaling is completed */
+	ufshcd_hold(hba, false);
+
+out:
 	return ret;
 }
 
@@ -1160,6 +1170,7 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba)
 {
 	up_write(&hba->clk_scaling_lock);
 	ufshcd_scsi_unblock_requests(hba);
+	ufshcd_release(hba);
 }
 
 /**
@@ -1175,12 +1186,9 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
 {
 	int ret = 0;
 
-	/* let's not get into low power until clock scaling is completed */
-	ufshcd_hold(hba, false);
-
 	ret = ufshcd_clock_scaling_prepare(hba);
 	if (ret)
-		goto out;
+		return ret;
 
 	/* scale down the gear before scaling down clocks */
 	if (!scale_up) {
@@ -1212,8 +1220,6 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
 
 out_unprepare:
 	ufshcd_clock_scaling_unprepare(hba);
-out:
-	ufshcd_release(hba);
 	return ret;
 }
 
@@ -1487,7 +1493,7 @@ static ssize_t ufshcd_clkscale_enable_show(struct device *dev,
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
-	return snprintf(buf, PAGE_SIZE, "%d\n", hba->clk_scaling.is_allowed);
+	return snprintf(buf, PAGE_SIZE, "%d\n", hba->clk_scaling.is_enabled);
 }
 
 static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
@@ -1496,12 +1502,20 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 	u32 value;
 	int err;
+	unsigned long flags;
+	bool update = true;
 
 	if (kstrtou32(buf, 0, &value))
 		return -EINVAL;
 
 	value = !!value;
-	if (value == hba->clk_scaling.is_allowed)
+	spin_lock_irqsave(hba->host->host_lock, flags);
+	if (value == hba->clk_scaling.is_enabled)
+		update = false;
+	else
+		hba->clk_scaling.is_enabled = value;
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	if (!update)
 		goto out;
 
 	pm_runtime_get_sync(hba->dev);
@@ -1510,8 +1524,6 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
 	cancel_work_sync(&hba->clk_scaling.suspend_work);
 	cancel_work_sync(&hba->clk_scaling.resume_work);
 
-	hba->clk_scaling.is_allowed = value;
-
 	if (value) {
 		ufshcd_resume_clkscaling(hba);
 	} else {
@@ -1845,8 +1857,6 @@ static void ufshcd_init_clk_scaling(struct ufs_hba *hba)
 	snprintf(wq_name, sizeof(wq_name), "ufs_clkscaling_%d",
 		 hba->host->host_no);
 	hba->clk_scaling.workq = create_singlethread_workqueue(wq_name);
-
-	ufshcd_clkscaling_init_sysfs(hba);
 }
 
 static void ufshcd_exit_clk_scaling(struct ufs_hba *hba)
@@ -1854,6 +1864,8 @@ static void ufshcd_exit_clk_scaling(struct ufs_hba *hba)
 	if (!ufshcd_is_clkscaling_supported(hba))
 		return;
 
+	if (hba->devfreq)
+		device_remove_file(hba->dev, &hba->clk_scaling.enable_attr);
 	destroy_workqueue(hba->clk_scaling.workq);
 	ufshcd_devfreq_remove(hba);
 }
@@ -1918,7 +1930,7 @@ static void ufshcd_clk_scaling_start_busy(struct ufs_hba *hba)
 	if (!hba->clk_scaling.active_reqs++)
 		queue_resume_work = true;
 
-	if (!hba->clk_scaling.is_allowed || hba->pm_op_in_progress)
+	if (!hba->clk_scaling.is_enabled || hba->pm_op_in_progress)
 		return;
 
 	if (queue_resume_work)
@@ -4987,7 +4999,8 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba,
 				complete(hba->dev_cmd.complete);
 			}
 		}
-		if (ufshcd_is_clkscaling_supported(hba))
+		if (ufshcd_is_clkscaling_supported(hba) &&
+		    hba->clk_scaling.active_reqs > 0)
 			hba->clk_scaling.active_reqs--;
 	}
 
@@ -5650,18 +5663,25 @@ static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
 		ufshcd_vops_resume(hba, UFS_RUNTIME_PM);
 	} else {
 		ufshcd_hold(hba, false);
-		if (hba->clk_scaling.is_allowed) {
+		if (hba->clk_scaling.is_enabled) {
 			cancel_work_sync(&hba->clk_scaling.suspend_work);
 			cancel_work_sync(&hba->clk_scaling.resume_work);
 			ufshcd_suspend_clkscaling(hba);
 		}
 	}
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = false;
+	up_write(&hba->clk_scaling_lock);
 }
 
 static void ufshcd_err_handling_unprepare(struct ufs_hba *hba)
 {
 	ufshcd_release(hba);
-	if (hba->clk_scaling.is_allowed)
+
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = true;
+	up_write(&hba->clk_scaling_lock);
+	if (hba->clk_scaling.is_enabled)
 		ufshcd_resume_clkscaling(hba);
 	pm_runtime_put(hba->dev);
 }
@@ -7620,12 +7640,14 @@ static int ufshcd_add_lus(struct ufs_hba *hba)
 			sizeof(struct ufs_pa_layer_attr));
 		hba->clk_scaling.saved_pwr_info.is_valid = true;
 		if (!hba->devfreq) {
+			hba->clk_scaling.is_allowed = true;
 			ret = ufshcd_devfreq_init(hba);
 			if (ret)
 				goto out;
-		}
 
-		hba->clk_scaling.is_allowed = true;
+			hba->clk_scaling.is_enabled = true;
+			ufshcd_clkscaling_init_sysfs(hba);
+		}
 	}
 
 	ufs_bsg_probe(hba);
@@ -8491,11 +8513,14 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	ufshcd_hold(hba, false);
 	hba->clk_gating.is_suspended = true;
 
-	if (hba->clk_scaling.is_allowed) {
+	if (hba->clk_scaling.is_enabled) {
 		cancel_work_sync(&hba->clk_scaling.suspend_work);
 		cancel_work_sync(&hba->clk_scaling.resume_work);
 		ufshcd_suspend_clkscaling(hba);
 	}
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = false;
+	up_write(&hba->clk_scaling_lock);
 
 	if (req_dev_pwr_mode == UFS_ACTIVE_PWR_MODE &&
 			req_link_state == UIC_LINK_ACTIVE_STATE) {
@@ -8592,8 +8617,6 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	goto out;
 
 set_link_active:
-	if (hba->clk_scaling.is_allowed)
-		ufshcd_resume_clkscaling(hba);
 	ufshcd_vreg_set_hpm(hba);
 	if (ufshcd_is_link_hibern8(hba) && !ufshcd_uic_hibern8_exit(hba))
 		ufshcd_set_link_active(hba);
@@ -8603,7 +8626,10 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	if (!ufshcd_set_dev_pwr_mode(hba, UFS_ACTIVE_PWR_MODE))
 		ufshcd_disable_auto_bkops(hba);
 enable_gating:
-	if (hba->clk_scaling.is_allowed)
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = true;
+	up_write(&hba->clk_scaling_lock);
+	if (hba->clk_scaling.is_enabled)
 		ufshcd_resume_clkscaling(hba);
 	hba->clk_gating.is_suspended = false;
 	hba->dev_info.b_rpm_dev_flush_capable = false;
@@ -8701,7 +8727,10 @@ static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 
 	hba->clk_gating.is_suspended = false;
 
-	if (hba->clk_scaling.is_allowed)
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = true;
+	up_write(&hba->clk_scaling_lock);
+	if (hba->clk_scaling.is_enabled)
 		ufshcd_resume_clkscaling(hba);
 
 	/* Enable Auto-Hibernate if configured */
@@ -8725,8 +8754,6 @@ static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	ufshcd_vreg_set_lpm(hba);
 disable_irq_and_vops_clks:
 	ufshcd_disable_irq(hba);
-	if (hba->clk_scaling.is_allowed)
-		ufshcd_suspend_clkscaling(hba);
 	ufshcd_setup_clocks(hba, false);
 	if (ufshcd_is_clkgating_allowed(hba)) {
 		hba->clk_gating.state = CLKS_OFF;
@@ -8915,6 +8942,8 @@ int ufshcd_shutdown(struct ufs_hba *hba)
 
 	pm_runtime_get_sync(hba->dev);
 
+	ufshcd_exit_clk_scaling(hba);
+
 	ret = ufshcd_suspend(hba, UFS_SHUTDOWN_PM);
 out:
 	if (ret)
@@ -8944,8 +8973,6 @@ void ufshcd_remove(struct ufs_hba *hba)
 
 	ufshcd_exit_clk_scaling(hba);
 	ufshcd_exit_clk_gating(hba);
-	if (ufshcd_is_clkscaling_supported(hba))
-		device_remove_file(hba->dev, &hba->clk_scaling.enable_attr);
 	ufshcd_hba_exit(hba);
 }
 EXPORT_SYMBOL_GPL(ufshcd_remove);
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index e0f00a4..9fcecba 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -382,6 +382,7 @@ struct ufs_saved_pwr_info {
  * @workq: workqueue to schedule devfreq suspend/resume work
  * @suspend_work: worker to suspend devfreq
  * @resume_work: worker to resume devfreq
+ * @is_enabled: tracks if scaling is currently enabled or not
  * @is_allowed: tracks if scaling is currently allowed or not
  * @is_busy_started: tracks if busy period has started or not
  * @is_suspended: tracks if devfreq is suspended or not
@@ -396,6 +397,7 @@ struct ufs_clk_scaling {
 	struct workqueue_struct *workq;
 	struct work_struct suspend_work;
 	struct work_struct resume_work;
+	bool is_enabled;
 	bool is_allowed;
 	bool is_busy_started;
 	bool is_suspended;
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.


  reply	other threads:[~2020-12-13 16:35 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-13 16:31 [PATCH v4 0/3] Three changes related with UFS clock scaling Can Guo
2020-12-13 16:31 ` Can Guo [this message]
2020-12-15  5:43   ` [PATCH v4 1/3] scsi: ufs: Protect some contexts from unexpected " Stanley Chu
2020-12-18  6:26     ` Can Guo
2020-12-16 13:31   ` Bean Huo
2020-12-13 16:31 ` [PATCH v4 2/3] scsi: ufs: Clean up ufshcd_exit_clk_scaling/gating() Can Guo
2020-12-15  5:55   ` Stanley Chu
2020-12-16 14:18   ` Bean Huo
2020-12-13 16:31 ` [PATCH v4 3/3] scsi: ufs: Revert "Make sure clk scaling happens only when HBA is runtime ACTIVE" Can Guo
2020-12-15  6:15   ` Stanley Chu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1607877104-8916-2-git-send-email-cang@codeaurora.org \
    --to=cang@codeaurora.org \
    --cc=alim.akhtar@samsung.com \
    --cc=asutoshd@codeaurora.org \
    --cc=avri.altman@wdc.com \
    --cc=beanhuo@micron.com \
    --cc=bvanassche@acm.org \
    --cc=hongwus@codeaurora.org \
    --cc=jejb@linux.ibm.com \
    --cc=kernel-team@android.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-scsi@vger.kernel.org \
    --cc=martin.petersen@oracle.com \
    --cc=nguyenb@codeaurora.org \
    --cc=rnayak@codeaurora.org \
    --cc=salyzyn@google.com \
    --cc=saravanak@google.com \
    --cc=satyat@google.com \
    --cc=stanley.chu@mediatek.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).