Re: [PATCH v2] drm/xe/ufence: Flush xe ordered_wq in case of ufence timeout

[John Harrison <john.c.harrison@intel.com>]

On 10/25/2024 09:03, Nirmoy Das wrote:
> On 10/24/2024 6:32 PM, Jani Nikula wrote:
>> On Thu, 24 Oct 2024, Nirmoy Das <nirmoy.das@intel.com> wrote:
>>> Flush xe ordered_wq in case of ufence timeout which is observed
>>> on LNL and that points to the recent scheduling issue with E-cores.
>>>
>>> This is similar to the recent fix:
>>> commit e51527233804 ("drm/xe/guc/ct: Flush g2h worker in case of g2h
>>> response timeout") and should be removed once there is E core
>>> scheduling fix.
>>>
>>> v2: Add platform check(Himal)
>>>      s/__flush_workqueue/flush_workqueue(Jani)
>>>
>>> Cc: Badal Nilawar <badal.nilawar@intel.com>
>>> Cc: Jani Nikula <jani.nikula@intel.com>
>>> Cc: Matthew Auld <matthew.auld@intel.com>
>>> Cc: John Harrison <John.C.Harrison@Intel.com>
>>> Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
>>> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
>>> Cc: <stable@vger.kernel.org> # v6.11+
>>> Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2754
>>> Suggested-by: Matthew Brost <matthew.brost@intel.com>
>>> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
>>> Reviewed-by: Matthew Brost <matthew.brost@intel.com>
>>> ---
>>>   drivers/gpu/drm/xe/xe_wait_user_fence.c | 14 ++++++++++++++
>>>   1 file changed, 14 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/xe/xe_wait_user_fence.c b/drivers/gpu/drm/xe/xe_wait_user_fence.c
>>> index f5deb81eba01..78a0ad3c78fe 100644
>>> --- a/drivers/gpu/drm/xe/xe_wait_user_fence.c
>>> +++ b/drivers/gpu/drm/xe/xe_wait_user_fence.c
>>> @@ -13,6 +13,7 @@
>>>   #include "xe_device.h"
>>>   #include "xe_gt.h"
>>>   #include "xe_macros.h"
>>> +#include "compat-i915-headers/i915_drv.h"
>> Sorry, you just can't use this in xe core. At all. Not even a little
>> bit. It's purely for i915 display compat code.
>>
>> If you need it for the LNL platform check, you need to use:
>>
>> 	xe->info.platform == XE_LUNARLAKE
>
> Will do that. That macro looked odd but I didn't know a better way.
>
>> Although platform checks in xe code are generally discouraged.
>
> This issue unfortunately depending on platform instead of graphics IP.
But isn't this issue dependent upon the CPU platform not the graphics 
platform? As in, a DG2 card plugged in to a LNL host will also have this 
issue. So testing any graphics related value is technically incorrect.

John.

>
>
> Thanks,
>
> Nirmoy
>
>> BR,
>> Jani.
>>
>>
>>
>>>   #include "xe_exec_queue.h"
>>>   
>>>   static int do_compare(u64 addr, u64 value, u64 mask, u16 op)
>>> @@ -155,6 +156,19 @@ int xe_wait_user_fence_ioctl(struct drm_device *dev, void *data,
>>>   		}
>>>   
>>>   		if (!timeout) {
>>> +			if (IS_LUNARLAKE(xe)) {
>>> +				/*
>>> +				 * This is analogous to e51527233804 ("drm/xe/guc/ct: Flush g2h
>>> +				 * worker in case of g2h response timeout")
>>> +				 *
>>> +				 * TODO: Drop this change once workqueue scheduling delay issue is
>>> +				 * fixed on LNL Hybrid CPU.
>>> +				 */
>>> +				flush_workqueue(xe->ordered_wq);
>>> +				err = do_compare(addr, args->value, args->mask, args->op);
>>> +				if (err <= 0)
>>> +					break;
>>> +			}
>>>   			err = -ETIME;
>>>   			break;
>>>   		}