[PATCH v2] drm/xe/guc: Configure TLB timeout based on CT buffer size

[Nirmoy Das]

GuC TLB invalidation depends on GuC to process the request from the CT
queue and then the real time to invalidate TLB. Add a function to return
overestimated possible time a TLB inval H2G might take which can be used
as timeout value for TLB invalidation wait time.

v2: Address reviews from Michal.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1622
Cc: Matthew Brost <matthew.brost at intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Suggested-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das at intel.com>
---
 drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c |  7 ++++++-
 drivers/gpu/drm/xe/xe_guc_ct.c              | 13 +++++++++++++
 drivers/gpu/drm/xe/xe_guc_ct.h              |  2 ++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
index e1f1ccb01143..6fc85f711074 100644
--- a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
+++ b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
@@ -17,7 +17,12 @@
 #include "xe_trace.h"
 #include "regs/xe_guc_regs.h"
 
-#define TLB_TIMEOUT	(HZ / 4)
+/**
+ * TLB inval depends on pending commands in the CT queue and then the real
+ * invalidation time. Double up the time to process full CT queue
+ * just to be on the safe side.
+ */
+#define TLB_TIMEOUT	(xe_ct_full_queue_proc_time_jiffies() * 2)
 
 static void xe_gt_tlb_fence_timeout(struct work_struct *work)
 {
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
index 873d1bcbedd7..0cdf0d4d20e5 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -112,6 +112,19 @@ ct_to_xe(struct xe_guc_ct *ct)
 #define CTB_G2H_BUFFER_SIZE	(4 * CTB_H2G_BUFFER_SIZE)
 #define G2H_ROOM_BUFFER_SIZE	(CTB_G2H_BUFFER_SIZE / 4)
 
+/**
+ * xe_ct_full_queue_proc_time_jiffies - Return maximum time to process a full CT command queue
+ *
+ * Observation is that A 4KB buffer full of commands takes a little over a second to process.
+ * Use that to calculate maximum time to process a full CT command queue.
+ *
+ * Return: Maximum time to process the full CT queue in jiffies.
+ */
+long xe_ct_full_queue_proc_time_jiffies(void)
+{
+	return (CTB_H2G_BUFFER_SIZE * HZ) / SZ_4K;
+}
+
 static size_t guc_ct_size(void)
 {
 	return 2 * CTB_DESC_SIZE + CTB_H2G_BUFFER_SIZE +
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.h b/drivers/gpu/drm/xe/xe_guc_ct.h
index 105bb8e99a8d..57280f82dc35 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.h
+++ b/drivers/gpu/drm/xe/xe_guc_ct.h
@@ -64,4 +64,6 @@ xe_guc_ct_send_block_no_fail(struct xe_guc_ct *ct, const u32 *action, u32 len)
 	return xe_guc_ct_send_recv_no_fail(ct, action, len, NULL);
 }
 
+long xe_ct_full_queue_proc_time_jiffies(void);
+
 #endif
-- 
2.42.0