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* [PATCH v2 1/2] drm/i915: Don't use DDB allocation when choosing gen9 watermark method
@ 2018-12-11  1:05 Matt Roper
  2018-12-11  1:05 ` [PATCH v2 2/2] drm/i915: Switch to level-based DDB allocation algorithm (v3) Matt Roper
                   ` (3 more replies)
  0 siblings, 4 replies; 9+ messages in thread
From: Matt Roper @ 2018-12-11  1:05 UTC (permalink / raw)
  To: intel-gfx

The bspec gives an if/else chain for choosing whether to use "method 1"
or "method 2" for calculating the watermark "Selected Result Blocks"
value for a plane.  One of the branches of the if chain is:

        "Else If ('plane buffer allocation' is known and (plane buffer
        allocation / plane blocks per line) >=1)"

Since our driver currently calculates DDB allocations first and the
actual watermark values second, the plane buffer allocation is known at
this point in our code and we include this test in our driver's logic.
However we plan to soon move to a "watermarks first, ddb allocation
second" sequence where we won't know the DDB allocation at this point.
Let's drop this arm of the if/else statement (effectively considering
the DDB allocation unknown) as an independent patch so that any
regressions can be more accurately bisected to either the different
watermark value (in this patch) or the new DDB allocation (in the next
patch).

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2bba5315b764..bf970cf7b8a5 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4761,13 +4761,6 @@ static int skl_compute_plane_wm(const struct intel_crtc_state *cstate,
 		     wp->dbuf_block_size < 1) &&
 		     (wp->plane_bytes_per_line / wp->dbuf_block_size < 1)) {
 			selected_result = method2;
-		} else if (ddb_allocation >=
-			 fixed16_to_u32_round_up(wp->plane_blocks_per_line)) {
-			if (IS_GEN9(dev_priv) &&
-			    !IS_GEMINILAKE(dev_priv))
-				selected_result = min_fixed16(method1, method2);
-			else
-				selected_result = method2;
 		} else if (latency >= wp->linetime_us) {
 			if (IS_GEN9(dev_priv) &&
 			    !IS_GEMINILAKE(dev_priv))
-- 
2.14.4

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^ permalink raw reply related	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2018-12-11 16:28 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-12-11  1:05 [PATCH v2 1/2] drm/i915: Don't use DDB allocation when choosing gen9 watermark method Matt Roper
2018-12-11  1:05 ` [PATCH v2 2/2] drm/i915: Switch to level-based DDB allocation algorithm (v3) Matt Roper
2018-12-11 15:59   ` Ville Syrjälä
2018-12-11 16:11     ` Matt Roper
2018-12-11 16:21       ` Ville Syrjälä
2018-12-11 16:28         ` Ville Syrjälä
2018-12-11  1:27 ` ✗ Fi.CI.SPARSE: warning for series starting with [v2,1/2] drm/i915: Don't use DDB allocation when choosing gen9 watermark method Patchwork
2018-12-11  1:45 ` ✓ Fi.CI.BAT: success " Patchwork
2018-12-11  3:37 ` ✗ Fi.CI.IGT: failure " Patchwork

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