Neither vtotal nor drm_mode_vrefresh contain a value that is premultiplied by 100 making the x100 variable name incorrect and resulting in vclks_line to become 100 times larger than it is supposed to be. The hardware counts 100 clockticks too many before tearcheck, leading to severe panel issues on at least the Sony Xperia lineup.
This is likely an artifact from the original MDSS DSI panel driver where the calculation [1] corrected for a premultiplied reference framerate by 100 [2]. It does not appear that the above values were ever premultiplied in the history of the DRM MDP5 driver.
With this change applied the value written to the SYNC_CONFIG_VSYNC register is now identical to downstream kernels.
[1]: https://source.codeaurora.org/quic/la/kernel/msm-3.18/tree/drivers/video/msm... [2]: https://source.codeaurora.org/quic/la/kernel/msm-3.18/tree/drivers/video/msm...
Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@somainline.org Signed-off-by: Marijn Suijten marijn.suijten@somainline.org --- drivers/gpu/drm/msm/disp/mdp5/mdp5_cmd_encoder.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
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 2d5ac03dbc17..0bda4257823a 100644 --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cmd_encoder.c +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cmd_encoder.c @@ -20,7 +20,7 @@ static int pingpong_tearcheck_setup(struct drm_encoder *encoder, { struct mdp5_kms *mdp5_kms = get_kms(encoder); struct device *dev = encoder->dev->dev; - u32 total_lines_x100, vclks_line, cfg; + u32 total_lines, vclks_line, cfg; long vsync_clk_speed; struct mdp5_hw_mixer *mixer = mdp5_crtc_get_mixer(encoder->crtc); int pp_id = mixer->pp; @@ -30,8 +30,8 @@ static int pingpong_tearcheck_setup(struct drm_encoder *encoder, return -EINVAL; }
- total_lines_x100 = mode->vtotal * drm_mode_vrefresh(mode); - if (!total_lines_x100) { + total_lines = mode->vtotal * drm_mode_vrefresh(mode); + if (!total_lines) { DRM_DEV_ERROR(dev, "%s: vtotal(%d) or vrefresh(%d) is 0\n", __func__, mode->vtotal, drm_mode_vrefresh(mode)); return -EINVAL; @@ -43,7 +43,7 @@ static int pingpong_tearcheck_setup(struct drm_encoder *encoder, vsync_clk_speed); return -EINVAL; } - vclks_line = vsync_clk_speed * 100 / total_lines_x100; + vclks_line = vsync_clk_speed / total_lines;
cfg = MDP5_PP_SYNC_CONFIG_VSYNC_COUNTER_EN | MDP5_PP_SYNC_CONFIG_VSYNC_IN_EN;