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 <[email protected]>
---
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.
Hi Can,
On Tue, 2021-01-19 at 03:52 -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 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 <[email protected]>
> ---
> 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)
Do we need to check hba->clk_scaling.active_reqs here?
if hba->clk_scaling.active_reqs is possibly decreased to negative value
here, then there may be something to be fixed?
Otherwise this patch looks good to me.
Thanks,
Stanley Chu
> 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;
On 2021-01-20 12:54, Stanley Chu wrote:
> Hi Can,
>
> On Tue, 2021-01-19 at 03:52 -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 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 <[email protected]>
>> ---
>> 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)
> Do we need to check hba->clk_scaling.active_reqs here?
>
> if hba->clk_scaling.active_reqs is possibly decreased to negative value
> here, then there may be something to be fixed?
No actual issue here, just want to be on the safe side.
Let me remove it in next version.
Thanks,
Can Guo.
>
> Otherwise this patch looks good to me.
>
> Thanks,
> Stanley Chu
>
>> 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;