linux-kernel - [PATCH v4 05/16] drm/msm/dpu: decide right side per last bit

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Message-Id: <20250116-sm8650-v6-13-hmd-deckard-mdss-quad-upstream-33-v4-5-74749c6eba33@linaro.org>
Date: Thu, 16 Jan 2025 15:25:54 +0800
From: Jun Nie <jun.nie@...aro.org>
To: Rob Clark <robdclark@...il.com>, 
 Abhinav Kumar <quic_abhinavk@...cinc.com>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Sean Paul <sean@...rly.run>, 
 Marijn Suijten <marijn.suijten@...ainline.org>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Jun Nie <jun.nie@...aro.org>
Subject: [PATCH v4 05/16] drm/msm/dpu: decide right side per last bit

Currently, only one pair of mixers is supported, so a non-zero counter
value is sufficient to identify the correct mixer within that pair.
However, future implementations may involve multiple mixer pairs. With
the current implementation, all mixers within the second pair would be
incorrectly selected as right mixer. To correctly select the mixer
within a pair, test the least significant bit of the counter. If the
least significant bit is not set, select the left mixer; otherwise,
select the right mixer for all pairs.

Signed-off-by: Jun Nie <jun.nie@...aro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index 7191b1a6d41b3..41c9d3e3e3c7c 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -369,11 +369,10 @@ static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
 static void _dpu_crtc_program_lm_output_roi(struct drm_crtc *crtc)
 {
 	struct dpu_crtc_state *crtc_state;
-	int lm_idx, lm_horiz_position;
+	int lm_idx;
 
 	crtc_state = to_dpu_crtc_state(crtc->state);
 
-	lm_horiz_position = 0;
 	for (lm_idx = 0; lm_idx < crtc_state->num_mixers; lm_idx++) {
 		const struct drm_rect *lm_roi = &crtc_state->lm_bounds[lm_idx];
 		struct dpu_hw_mixer *hw_lm = crtc_state->mixers[lm_idx].hw_lm;
@@ -384,7 +383,7 @@ static void _dpu_crtc_program_lm_output_roi(struct drm_crtc *crtc)
 
 		cfg.out_width = drm_rect_width(lm_roi);
 		cfg.out_height = drm_rect_height(lm_roi);
-		cfg.right_mixer = lm_horiz_position++;
+		cfg.right_mixer = lm_idx & 0x1;
 		cfg.flags = 0;
 		hw_lm->ops.setup_mixer_out(hw_lm, &cfg);
 	}

-- 
2.34.1