drm/msm/mdp5: Configure PP_SYNC_HEIGHT to double the vtotal

Leaving this at a close-to-maximum register value 0xFFF0 means it takes
very long for the MDSS to generate a software vsync interrupt when the
hardware TE interrupt doesn't arrive.  Configuring this to double the
vtotal (like some downstream kernels) leads to a frame to take at most
twice before the vsync signal, until hardware TE comes up.

In this case the hardware interrupt responsible for providing this
signal - "disp-te" gpio - is not hooked up to the mdp5 vsync/pp logic at
all.  This solves severe panel update issues observed on at least the
Xperia Loire and Tone series, until said gpio is properly hooked up to
an irq.

Suggested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Link: https://lore.kernel.org/r/20210406214726.131534-2-marijn.suijten@somainline.org
Signed-off-by: Rob Clark <robdclark@chromium.org>

diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cmd_encoder.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cmd_encoder.c
index ff2c1d583c7922a6c57f98910c658098b6eaef76..f6df4d3b14062d02e8c8961e8ed940113cb9766d 100644 (file)
--- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cmd_encoder.c
+++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cmd_encoder.c
@@ -49,9 +49,17 @@ static int pingpong_tearcheck_setup(struct drm_encoder *encoder,
                | MDP5_PP_SYNC_CONFIG_VSYNC_IN_EN;
        cfg |= MDP5_PP_SYNC_CONFIG_VSYNC_COUNT(vclks_line);
 
+       /*
+        * Tearcheck emits a blanking signal every vclks_line * vtotal * 2 ticks on
+        * the vsync_clk equating to roughly half the desired panel refresh rate.
+        * This is only necessary as stability fallback if interrupts from the
+        * panel arrive too late or not at all, but is currently used by default
+        * because these panel interrupts are not wired up yet.
+        */
        mdp5_write(mdp5_kms, REG_MDP5_PP_SYNC_CONFIG_VSYNC(pp_id), cfg);
        mdp5_write(mdp5_kms,
-               REG_MDP5_PP_SYNC_CONFIG_HEIGHT(pp_id), 0xfff0);
+               REG_MDP5_PP_SYNC_CONFIG_HEIGHT(pp_id), (2 * mode->vtotal));
+
        mdp5_write(mdp5_kms,
                REG_MDP5_PP_VSYNC_INIT_VAL(pp_id), mode->vdisplay);
        mdp5_write(mdp5_kms, REG_MDP5_PP_RD_PTR_IRQ(pp_id), mode->vdisplay + 1);