On Thu, Oct 24, 2024 at 10:14:21AM -0700, John Harrison wrote:

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.

+1, I think Lucas is suggesting something similar to this on the chat to
make sure we don't lose track of removing these W/A when this gets
fixed.

Matt

Sounds good. I will add LNL_FLUSH_WORKQUEUE() and use that for all the places we need this WA.

Regards,

Nirmoy

John.

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