[Intel-xe] [PATCH v2 3/3] drm/xe: Add CONFIG_DRM_XE_PREEMPT_TIMEOUT_COMPUTE

[Niranjana Vishwanathapura]

Allow preemption timeout for compute engines to be specified as a
config option. The purpose is actually to give compute tasks longer
time to reach a pre-emption point after a pre-emption request has been
issued. This is necessary because Gen12 does not support mid-thread
pre-emption and compute tasks can have long running threads.

v2: Change unit to microseconds (Tejas)

Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura at intel.com>
---
 drivers/gpu/drm/xe/Kconfig.profile | 12 ++++++++++++
 drivers/gpu/drm/xe/xe_hw_engine.c  |  8 +++++++-
 drivers/gpu/drm/xe/xe_hw_engine.h  |  5 +++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/Kconfig.profile b/drivers/gpu/drm/xe/Kconfig.profile
index a3655ee6978e..dd7f155371fa 100644
--- a/drivers/gpu/drm/xe/Kconfig.profile
+++ b/drivers/gpu/drm/xe/Kconfig.profile
@@ -31,6 +31,18 @@ config DRM_XE_PREEMPT_TIMEOUT
 	  an arbitration point and yield to HW before the timer expires, the
 	  HW will be reset to allow the more important context to execute.
 
+	  Value should be within the DRM_XE_PREEMPT_TIMEOUT_MIN/MAX limits.
+	  This is adjustable via XE_ENGINE_SET_PROPERTY_PREEMPTION_TIMEOUT.
+config DRM_XE_PREEMPT_TIMEOUT_COMPUTE
+	int "Preempt timeout for compute engines (us, jiffy granularity)"
+	default 7500000 # microseconds
+	help
+	  How long to wait (in microseconds) for a preemption event to occur
+	  when submitting a new context to a compute capable engine. If the
+	  current context does not hit an arbitration point and yield to HW
+	  before the timer expires, the HW will be reset to allow the more
+	  important context to execute.
+
 	  Value should be within the DRM_XE_PREEMPT_TIMEOUT_MIN/MAX limits.
 	  This is adjustable via XE_ENGINE_SET_PROPERTY_PREEMPTION_TIMEOUT.
 config DRM_XE_PREEMPT_TIMEOUT_MAX
diff --git a/drivers/gpu/drm/xe/xe_hw_engine.c b/drivers/gpu/drm/xe/xe_hw_engine.c
index 8e5153cada31..e9ce34faa2da 100644
--- a/drivers/gpu/drm/xe/xe_hw_engine.c
+++ b/drivers/gpu/drm/xe/xe_hw_engine.c
@@ -340,7 +340,11 @@ hw_engine_setup_default_state(struct xe_hw_engine *hwe)
 
 static u32 get_default_preempt_timeout(struct xe_hw_engine *hwe)
 {
-	return XE_HW_ENGINE_PREEMPT_TIMEOUT;
+	if (hwe->class == XE_ENGINE_CLASS_RENDER ||
+	    hwe->class == XE_ENGINE_CLASS_COMPUTE)
+		return XE_HW_ENGINE_PREEMPT_TIMEOUT_COMPUTE;
+	else
+		return XE_HW_ENGINE_PREEMPT_TIMEOUT;
 }
 
 static void hw_engine_init_early(struct xe_gt *gt, struct xe_hw_engine *hwe,
@@ -570,6 +574,8 @@ int xe_hw_engines_init_early(struct xe_gt *gt)
 
 	BUILD_BUG_ON(XE_HW_ENGINE_PREEMPT_TIMEOUT < XE_HW_ENGINE_PREEMPT_TIMEOUT_MIN);
 	BUILD_BUG_ON(XE_HW_ENGINE_PREEMPT_TIMEOUT > XE_HW_ENGINE_PREEMPT_TIMEOUT_MAX);
+	BUILD_BUG_ON(XE_HW_ENGINE_PREEMPT_TIMEOUT_COMPUTE < XE_HW_ENGINE_PREEMPT_TIMEOUT_MIN);
+	BUILD_BUG_ON(XE_HW_ENGINE_PREEMPT_TIMEOUT_COMPUTE > XE_HW_ENGINE_PREEMPT_TIMEOUT_MAX);
 
 	for (i = 0; i < ARRAY_SIZE(gt->hw_engines); i++)
 		hw_engine_init_early(gt, &gt->hw_engines[i], i);
diff --git a/drivers/gpu/drm/xe/xe_hw_engine.h b/drivers/gpu/drm/xe/xe_hw_engine.h
index 71968ee2f600..cee0b40a62a2 100644
--- a/drivers/gpu/drm/xe/xe_hw_engine.h
+++ b/drivers/gpu/drm/xe/xe_hw_engine.h
@@ -35,6 +35,11 @@ struct drm_printer;
 #else
 #define XE_HW_ENGINE_PREEMPT_TIMEOUT (640 * 1000)
 #endif
+#ifdef CONFIG_DRM_XE_PREEMPT_TIMEOUT_COMPUTE
+#define XE_HW_ENGINE_PREEMPT_TIMEOUT_COMPUTE CONFIG_DRM_XE_PREEMPT_TIMEOUT_COMPUTE
+#else
+#define XE_HW_ENGINE_PREEMPT_TIMEOUT_COMPUTE XE_HW_ENGINE_PREEMPT_TIMEOUT
+#endif
 #ifdef CONFIG_DRM_XE_PREEMPT_TIMEOUT_MIN
 #define XE_HW_ENGINE_PREEMPT_TIMEOUT_MIN CONFIG_DRM_XE_PREEMPT_TIMEOUT_MIN
 #else
-- 
2.21.0.rc0.32.g243a4c7e27