[PATCH 06/19] drm/i915/perf: Use helpers to process reports w.r.t. OA buffer size

[Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>]

DG2 has a new feature to supports OA buffer sizes up to 128Mb by
toggling a bit in OA_DEBUG. This would eventually be a user configurable
parameter. Use OA buffer vma size in all calculations with some helpers.

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_perf.c | 47 ++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 6fc4f0d8fc5a..18cc9a311b7e 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -385,6 +385,22 @@ static struct ctl_table_header *sysctl_header;
 
 static enum hrtimer_restart oa_poll_check_timer_cb(struct hrtimer *hrtimer);
 
+static inline u32 _oa_taken(struct i915_perf_stream * stream,
+			       u32 tail, u32 head)
+{
+	u32 size = stream->oa_buffer.vma->size;
+
+	return tail >= head ? tail - head : size - (head - tail);
+}
+
+static inline u32 _rewind_tail(struct i915_perf_stream * stream,
+			       u32 relative_hw_tail, u32 rewind_delta)
+{
+	return rewind_delta > relative_hw_tail ?
+	       stream->oa_buffer.vma->size - (rewind_delta - relative_hw_tail) :
+	       relative_hw_tail - rewind_delta;
+}
+
 void i915_oa_config_release(struct kref *ref)
 {
 	struct i915_oa_config *oa_config =
@@ -487,12 +503,14 @@ static bool oa_buffer_check_unlocked(struct i915_perf_stream *stream)
 	 * sizes need not be integral multiples or 64 or powers of 2.
 	 * Compute potentially partially landed report in the OA buffer
 	 */
-	partial_report_size = OA_TAKEN(hw_tail, stream->oa_buffer.tail);
+	partial_report_size =
+		_oa_taken(stream, hw_tail, stream->oa_buffer.tail);
 	partial_report_size %= report_size;
 
 	/* Subtract partial amount off the tail */
-	hw_tail = gtt_offset + ((hw_tail - partial_report_size) &
-				(stream->oa_buffer.vma->size - 1));
+	hw_tail = gtt_offset + _rewind_tail(stream,
+					    hw_tail - gtt_offset,
+					    partial_report_size);
 
 	now = ktime_get_mono_fast_ns();
 
@@ -527,16 +545,16 @@ static bool oa_buffer_check_unlocked(struct i915_perf_stream *stream)
 		 * memory in the order they were written to.
 		 * If not : (╯°□°）╯︵ ┻━┻
 		 */
-		while (OA_TAKEN(tail, aged_tail) >= report_size) {
+		while (_oa_taken(stream, tail, aged_tail) >= report_size) {
 			u32 *report32 = (void *)(stream->oa_buffer.vaddr + tail);
 
 			if (report32[0] != 0 || report32[1] != 0)
 				break;
 
-			tail = (tail - report_size) & (OA_BUFFER_SIZE - 1);
+			tail = _rewind_tail(stream, tail, report_size);
 		}
 
-		if (OA_TAKEN(hw_tail, tail) > report_size &&
+		if (_oa_taken(stream, hw_tail, tail) > report_size &&
 		    __ratelimit(&stream->perf->tail_pointer_race))
 			DRM_NOTE("unlanded report(s) head=0x%x "
 				 "tail=0x%x hw_tail=0x%x\n",
@@ -547,8 +565,9 @@ static bool oa_buffer_check_unlocked(struct i915_perf_stream *stream)
 		stream->oa_buffer.aging_timestamp = now;
 	}
 
-	pollin = OA_TAKEN(stream->oa_buffer.tail - gtt_offset,
-			  stream->oa_buffer.head - gtt_offset) >= report_size;
+	pollin = _oa_taken(stream,
+			   stream->oa_buffer.tail,
+			   stream->oa_buffer.head) >= report_size;
 
 	spin_unlock_irqrestore(&stream->oa_buffer.ptr_lock, flags);
 
@@ -679,11 +698,9 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 	int report_size = stream->oa_buffer.format_size;
 	u8 *oa_buf_base = stream->oa_buffer.vaddr;
 	u32 gtt_offset = i915_ggtt_offset(stream->oa_buffer.vma);
-	u32 mask = (OA_BUFFER_SIZE - 1);
 	size_t start_offset = *offset;
 	unsigned long flags;
-	u32 head, tail;
-	u32 taken;
+	u32 head, tail, size;
 	int ret = 0;
 
 	if (drm_WARN_ON(&uncore->i915->drm, !stream->enabled))
@@ -693,6 +710,7 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 
 	head = stream->oa_buffer.head;
 	tail = stream->oa_buffer.tail;
+	size = stream->oa_buffer.vma->size;
 
 	spin_unlock_irqrestore(&stream->oa_buffer.ptr_lock, flags);
 
@@ -711,16 +729,15 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 	 * all a power of two).
 	 */
 	if (drm_WARN_ONCE(&uncore->i915->drm,
-			  head > stream->oa_buffer.vma->size ||
-			  tail > stream->oa_buffer.vma->size,
+			  head > size || tail > size,
 			  "Inconsistent OA buffer pointers: head = %u, tail = %u\n",
 			  head, tail))
 		return -EIO;
 
 
 	for (/* none */;
-	     (taken = OA_TAKEN(tail, head));
-	     head = (head + report_size) & mask) {
+	     _oa_taken(stream, tail, head);
+	     head = (head + report_size) % size) {
 		u8 *report = oa_buf_base + head;
 		u32 *report32 = (void *)report;
 		u32 ctx_id;
-- 
2.25.1