From: Stanley Chu <stanley.chu@mediatek.com>
To: Can Guo <cang@codeaurora.org>
Cc: <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>,
"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>,
Bean Huo <beanhuo@micron.com>,
"Bart Van Assche" <bvanassche@acm.org>,
Satya Tangirala <satyat@google.com>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 1/3] scsi: ufs: Protect some contexts from unexpected clock scaling
Date: Tue, 15 Dec 2020 13:43:31 +0800 [thread overview]
Message-ID: <1608011011.10163.9.camel@mtkswgap22> (raw)
In-Reply-To: <1607877104-8916-2-git-send-email-cang@codeaurora.org>
Hi Can,
On Sun, 2020-12-13 at 08:31 -0800, Can Guo wrote:
> 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;
Perhaps moving this line after ufshcd_devfreq_init() is successful?
> 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;
Now there are more and more "similar boolean attributes" regarding
clk-scaling control, maybe add more comprehensive comments to describe
them?
Otherwise this patch looks good to me.
Feel free to add
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
next prev parent reply other threads:[~2020-12-15 5:46 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1607877104-8916-1-git-send-email-cang@codeaurora.org>
2020-12-13 16:31 ` [PATCH v4 1/3] scsi: ufs: Protect some contexts from unexpected clock scaling Can Guo
2020-12-15 5:43 ` Stanley Chu [this message]
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
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