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

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

On 10/24/2024 08:18, Nirmoy Das 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"
>   #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);
If we are having multiple instances of this workaround, can we wrap them 
up in as 'LNL_FLUSH_WORKQUEUE(q)' or some such? Put the IS_LNL check 
inside the macro and make it pretty obvious exactly where all the 
instances are by having a single macro name to search for.

John.

> +				err = do_compare(addr, args->value, args->mask, args->op);
> +				if (err <= 0)
> +					break;
> +			}
>   			err = -ETIME;
>   			break;
>   		}