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

[Lucas De Marchi]

On Thu, May 08, 2025 at 11:28:29AM +0530, Poosa, Karthik wrote:
>
>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.

no, not without proper justification. I see no reason to wait for it in
pm runtime resume. We shouldn't sprinkle sleeps in the driver to be
prudent.

Lucas De Marchi

>>>
>>>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
>>>