lkml.org 
[lkml]   [2020]   [Dec]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/2] scsi: ufs: Protect some contexts from unexpected clock scaling
On 2020-12-11 01:34, Bean Huo wrote:
> Hi Can
>
> On Wed, 2020-12-09 at 05:35 -0800, Can Guo wrote:
>>
>>
>> @@ -1160,6 +1166,7 @@ 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 +1182,9 @@ 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 +1216,6 @@ 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;
>> }
>
> I didn't understand why moving ufshcd_hold/ufshcd_release into
> ufshcd_clock_scaling_prepare()/ufshcd_clock_scaling_unprepare().
>

Say you change devfreq's governor to performance after UFS host
has entered runtime suspend.

governor_store
devfreq_performance_handler
update_devfreq
devfreq_set_target
ufshcd_devfreq_target
ufshcd_devfreq_scale

When ufshcd_devfreq_scale() calls ufshcd_hold() when host is already
runtime suspended, guess what, NoC issues. So clk_scaling.is_allowed
should be checked first.

Regards,

Can Guo.

>
>>
>> @@ -1294,15 +1296,8 @@ static int ufshcd_devfreq_target(struct device
>> *dev,
>> }
>> spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
>>
>> - pm_runtime_get_noresume(hba->dev);
>> - if (!pm_runtime_active(hba->dev)) {
>> - pm_runtime_put_noidle(hba->dev);
>> - ret = -EAGAIN;
>> - goto out;
>> - }
>> start = ktime_get();
>> ret = ufshcd_devfreq_scale(hba, scale_up);
>> - pm_runtime_put(hba->dev);
>>
>
> which branch are you working on? I didn't see this part codes in the
> branch 5.11/scsi-queue and 5.11/scsi-staging.
>
> Bean

\
 
 \ /
  Last update: 2020-12-11 02:12    [W:0.049 / U:0.424 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site