[Intel-xe] [PATCH v2 2/3] drm/xe: Add CONFIG_DRM_XE_PREEMPT_TIMEOUT

[Niranjana Vishwanathapura]

Allow preemption timeout to be specified as a config option.

v2: Change unit to microseconds (Tejas)

Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura at intel.com>
---
 drivers/gpu/drm/xe/Kconfig.profile | 11 +++++++++++
 drivers/gpu/drm/xe/xe_hw_engine.c  | 11 ++++++++++-
 drivers/gpu/drm/xe/xe_hw_engine.h  |  5 +++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/Kconfig.profile b/drivers/gpu/drm/xe/Kconfig.profile
index 9ad487647ca1..a3655ee6978e 100644
--- a/drivers/gpu/drm/xe/Kconfig.profile
+++ b/drivers/gpu/drm/xe/Kconfig.profile
@@ -22,6 +22,17 @@ config DRM_XE_TIMESLICE_MIN
 	help
 	  Configures the default min timeslice duration between multiple
 	  contexts by guc scheduling.
+config DRM_XE_PREEMPT_TIMEOUT
+	int "Preempt timeout (us, jiffy granularity)"
+	default 640000 # microseconds
+	help
+	  How long to wait (in microseconds) for a preemption event to occur
+	  when submitting a new context. 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
 	int "Default max  preempt timeout (us)"
 	default 10000000 # microseconds
diff --git a/drivers/gpu/drm/xe/xe_hw_engine.c b/drivers/gpu/drm/xe/xe_hw_engine.c
index c44540684462..8e5153cada31 100644
--- a/drivers/gpu/drm/xe/xe_hw_engine.c
+++ b/drivers/gpu/drm/xe/xe_hw_engine.c
@@ -338,6 +338,11 @@ hw_engine_setup_default_state(struct xe_hw_engine *hwe)
 	xe_rtp_process_to_sr(&ctx, engine_entries, &hwe->reg_sr);
 }
 
+static u32 get_default_preempt_timeout(struct xe_hw_engine *hwe)
+{
+	return XE_HW_ENGINE_PREEMPT_TIMEOUT;
+}
+
 static void hw_engine_init_early(struct xe_gt *gt, struct xe_hw_engine *hwe,
 				 enum xe_hw_engine_id id)
 {
@@ -370,7 +375,8 @@ static void hw_engine_init_early(struct xe_gt *gt, struct xe_hw_engine *hwe,
 		hwe->eclass->sched_props.timeslice_us = 1 * 1000;
 		hwe->eclass->sched_props.timeslice_min = XE_HW_ENGINE_TIMESLICE_MIN;
 		hwe->eclass->sched_props.timeslice_max = XE_HW_ENGINE_TIMESLICE_MAX;
-		hwe->eclass->sched_props.preempt_timeout_us = 640 * 1000;
+
+		hwe->eclass->sched_props.preempt_timeout_us = get_default_preempt_timeout(hwe);
 		hwe->eclass->sched_props.preempt_timeout_min = XE_HW_ENGINE_PREEMPT_TIMEOUT_MIN;
 		hwe->eclass->sched_props.preempt_timeout_max = XE_HW_ENGINE_PREEMPT_TIMEOUT_MAX;
 		/* Record default props */
@@ -562,6 +568,9 @@ int xe_hw_engines_init_early(struct xe_gt *gt)
 	read_copy_fuses(gt);
 	read_compute_fuses(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);
+
 	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 3d37d6d44261..71968ee2f600 100644
--- a/drivers/gpu/drm/xe/xe_hw_engine.h
+++ b/drivers/gpu/drm/xe/xe_hw_engine.h
@@ -30,6 +30,11 @@ struct drm_printer;
 #else
 #define XE_HW_ENGINE_TIMESLICE_MAX (10 * 1000 * 1000)
 #endif
+#ifdef CONFIG_DRM_XE_PREEMPT_TIMEOUT
+#define XE_HW_ENGINE_PREEMPT_TIMEOUT CONFIG_DRM_XE_PREEMPT_TIMEOUT
+#else
+#define XE_HW_ENGINE_PREEMPT_TIMEOUT (640 * 1000)
+#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