linux-kernel.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, ziqichen@codeaurora.org,
	linux-scsi@vger.kernel.org, kernel-team@android.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>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Satya Tangirala <satyat@google.com>,
	linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v10 1/3] scsi: ufs: Protect some contexts from unexpected clock scaling
Date: Tue, 19 Jan 2021 03:52:59 -0800	[thread overview]
Message-ID: <1611057183-6925-2-git-send-email-cang@codeaurora.org> (raw)
In-Reply-To: <1611057183-6925-1-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 devfreq sysfs nodes like min/max_freq and
governor even after devfreq is suspended. Moreover, mere suspending devfreq
cannot synchroinze a clock scaling which has already been invoked through
these sysfs nodes. Add one more flag in struct clk_scaling and wrap the
entire func ufshcd_devfreq_scale() with the clk_scaling_lock, so that we
can use this flag and clk_scaling_lock to control and synchronize clock
scaling invoked through devfreq sysfs nodes.

Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 83 +++++++++++++++++++++++++++++------------------
 drivers/scsi/ufs/ufshcd.h |  6 +++-
 2 files changed, 56 insertions(+), 33 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 53fd59c..ba62d84 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1201,19 +1201,30 @@ 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 ||
+	    ufshcd_wait_for_doorbell_clr(hba, DOORBELL_CLR_TOUT_US)) {
 		ret = -EBUSY;
 		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;
 }
 
-static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba)
+static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, bool writelock)
 {
-	up_write(&hba->clk_scaling_lock);
+	if (writelock)
+		up_write(&hba->clk_scaling_lock);
+	else
+		up_read(&hba->clk_scaling_lock);
 	ufshcd_scsi_unblock_requests(hba);
+	ufshcd_release(hba);
 }
 
 /**
@@ -1228,13 +1239,11 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba)
 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);
+	bool is_writelock = true;
 
 	ret = ufshcd_clock_scaling_prepare(hba);
 	if (ret)
-		goto out;
+		return ret;
 
 	/* scale down the gear before scaling down clocks */
 	if (!scale_up) {
@@ -1260,14 +1269,12 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
 	}
 
 	/* Enable Write Booster if we have scaled up else disable it */
-	up_write(&hba->clk_scaling_lock);
+	downgrade_write(&hba->clk_scaling_lock);
+	is_writelock = false;
 	ufshcd_wb_ctrl(hba, scale_up);
-	down_write(&hba->clk_scaling_lock);
 
 out_unprepare:
-	ufshcd_clock_scaling_unprepare(hba);
-out:
-	ufshcd_release(hba);
+	ufshcd_clock_scaling_unprepare(hba, is_writelock);
 	return ret;
 }
 
@@ -1541,7 +1548,7 @@ 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,
@@ -1555,7 +1562,7 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
 		return -EINVAL;
 
 	value = !!value;
-	if (value == hba->clk_scaling.is_allowed)
+	if (value == hba->clk_scaling.is_enabled)
 		goto out;
 
 	pm_runtime_get_sync(hba->dev);
@@ -1564,7 +1571,7 @@ 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;
+	hba->clk_scaling.is_enabled = value;
 
 	if (value) {
 		ufshcd_resume_clkscaling(hba);
@@ -1902,8 +1909,6 @@ 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)
@@ -1911,6 +1916,8 @@ static void ufshcd_exit_clk_scaling(struct ufs_hba *hba)
 	if (!ufshcd_is_clkscaling_supported(hba))
 		return;
 
+	if (hba->clk_scaling.enable_attr.attr.name)
+		device_remove_file(hba->dev, &hba->clk_scaling.enable_attr);
 	destroy_workqueue(hba->clk_scaling.workq);
 	ufshcd_devfreq_remove(hba);
 }
@@ -1975,7 +1982,7 @@ 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)
@@ -5093,7 +5100,8 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba,
 				update_scaling = true;
 			}
 		}
-		if (ufshcd_is_clkscaling_supported(hba) && update_scaling)
+		if (ufshcd_is_clkscaling_supported(hba) && update_scaling &&
+		    hba->clk_scaling.active_reqs > 0)
 			hba->clk_scaling.active_reqs--;
 	}
 
@@ -5759,18 +5767,24 @@ static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
 		ufshcd_vops_resume(hba, pm_op);
 	} 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);
 }
@@ -7750,12 +7764,14 @@ 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);
@@ -8672,11 +8688,14 @@ 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) {
@@ -8773,8 +8792,6 @@ 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);
 	/*
 	 * Device hardware reset is required to exit DeepSleep. Also, for
@@ -8798,7 +8815,10 @@ 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;
@@ -8901,7 +8921,10 @@ 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 */
@@ -8925,8 +8948,6 @@ 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;
@@ -9153,8 +9174,6 @@ 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 85f9d0f..d553e46 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -419,7 +419,10 @@ struct ufs_saved_pwr_info {
  * @suspend_work: worker to suspend devfreq
  * @resume_work: worker to resume devfreq
  * @min_gear: lowest HS gear to scale down to
- * @is_allowed: tracks if scaling is currently allowed or not
+ * @is_enabled: tracks if scaling is currently enabled or not, controlled by
+		clkscale_enable sysfs node
+ * @is_allowed: tracks if scaling is currently allowed or not, used to block
+		clock scaling which is not invoked from devfreq governor
  * @is_busy_started: tracks if busy period has started or not
  * @is_suspended: tracks if devfreq is suspended or not
  */
@@ -434,6 +437,7 @@ struct ufs_clk_scaling {
 	struct work_struct suspend_work;
 	struct work_struct resume_work;
 	u32 min_gear;
+	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:[~2021-01-19 12:07 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1611057183-6925-1-git-send-email-cang@codeaurora.org>
2021-01-19 11:52 ` Can Guo [this message]
2021-01-20  4:54   ` [PATCH v10 1/3] scsi: ufs: Protect some contexts from unexpected clock scaling Stanley Chu
2021-01-20  8:29     ` Can Guo
2021-01-19 11:53 ` [PATCH v10 2/3] scsi: ufs: Refactor ufshcd_init/exit_clk_scaling/gating() Can Guo
2021-01-20  5:05   ` Stanley Chu
2021-01-19 11:53 ` [PATCH v10 3/3] scsi: ufs: Revert "Make sure clk scaling happens only when HBA is runtime ACTIVE" Can Guo

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=1611057183-6925-2-git-send-email-cang@codeaurora.org \
    --to=cang@codeaurora.org \
    --cc=adrian.hunter@intel.com \
    --cc=alim.akhtar@samsung.com \
    --cc=asutoshd@codeaurora.org \
    --cc=avri.altman@wdc.com \
    --cc=beanhuo@micron.com \
    --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=satyat@google.com \
    --cc=stanley.chu@mediatek.com \
    --cc=ziqichen@codeaurora.org \
    /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).