[PATCH v1] drm/xe/pm: Wait for lmem ready in resume

[Poosa, Karthik]

On 22-04-2025 21:30, Lucas De Marchi wrote:
> On Thu, Apr 10, 2025 at 04:30:57PM +0530, Karthik Poosa wrote:
>> Add wait for LMEM ready during system and runtime resume.
>> This wait is there in probe and is missing during resume.
>>
>> Signed-off-by: Karthik Poosa <karthik.poosa at intel.com>
>> ---
>> drivers/gpu/drm/xe/xe_device.c | 2 +-
>> drivers/gpu/drm/xe/xe_device.h | 1 +
>> drivers/gpu/drm/xe/xe_pm.c     | 8 ++++++++
>> 3 files changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_device.c 
>> b/drivers/gpu/drm/xe/xe_device.c
>> index 75e753e0a682..4c0d9eb51d1f 100644
>> --- a/drivers/gpu/drm/xe/xe_device.c
>> +++ b/drivers/gpu/drm/xe/xe_device.c
>> @@ -630,7 +630,7 @@ static bool verify_lmem_ready(struct xe_device *xe)
>>     return !!val;
>> }
>>
>> -static int wait_for_lmem_ready(struct xe_device *xe)
>> +int wait_for_lmem_ready(struct xe_device *xe)
>> {
>>     unsigned long timeout, start;
>>
>> diff --git a/drivers/gpu/drm/xe/xe_device.h 
>> b/drivers/gpu/drm/xe/xe_device.h
>> index 0bc3bc8e6803..60bc92f9ab22 100644
>> --- a/drivers/gpu/drm/xe/xe_device.h
>> +++ b/drivers/gpu/drm/xe/xe_device.h
>> @@ -47,6 +47,7 @@ int xe_device_probe_early(struct xe_device *xe);
>> int xe_device_probe(struct xe_device *xe);
>> void xe_device_remove(struct xe_device *xe);
>> void xe_device_shutdown(struct xe_device *xe);
>> +int wait_for_lmem_ready(struct xe_device *xe);
>
> if you are exporting the function, please follow the naming:
> xe_device_*.
>
> However, I'm not sure this is really needed, particularly on pm runtime
> resume. At the very least it needs better explanation in the commit
> message. Do we have any known failures this is supposedly to fix?
>
> Lucas De Marchi
>
While there are no current issues without this check, it's a prudent 
measure to prevent any future problems.
>>
>> void xe_device_wmb(struct xe_device *xe);
>>
>> diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
>> index 4e112fbacada..2e59670660c1 100644
>> --- a/drivers/gpu/drm/xe/xe_pm.c
>> +++ b/drivers/gpu/drm/xe/xe_pm.c
>> @@ -182,6 +182,10 @@ int xe_pm_resume(struct xe_device *xe)
>>     if (err)
>>         return err;
>>
>> +    err = wait_for_lmem_ready(xe);
>> +    if (err)
>> +        goto err;
>> +
>>     xe_display_pm_resume_early(xe);
>>
>>     /*
>> @@ -478,6 +482,10 @@ int xe_pm_runtime_resume(struct xe_device *xe)
>>         if (err)
>>             goto out;
>>
>> +        err = wait_for_lmem_ready(xe);
>> +        if (err)
>> +            goto out;
>> +
>>         xe_display_pm_resume_early(xe);
>>
>>         /*
>> -- 
>> 2.25.1
>>