Messages in this thread | | | Date | Fri, 18 Dec 2020 14:26:06 +0800 | From | Can Guo <> | Subject | Re: [PATCH v4 1/3] scsi: ufs: Protect some contexts from unexpected clock scaling |
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On 2020-12-15 13:43, Stanley Chu wrote: > 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?
devfreq starts to work even before ufshcd_devfreq_init() returns, I don't want to block it, hence put it before ufshcd_devfreq_init(). If devfreq fails to initialize, clk_scaling and its related sysfs nodes anyways won't work and clk_scaling->is_enabled is false, so we are safe.
> >> 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.
Sure, I will give more words to the new flag.
Thanks,
Can Guo.
> > Feel free to add > Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
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