This is a note to let you know that I've just added the patch titled drm/msm/mdp5: Do not multiply vclk line count by 100 to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-msm-mdp5-do-not-multiply-vclk-line-count-by-100.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 122704217c2bca7bd359f230588460ca0d42d7cd Author: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx> Date: Tue Apr 6 23:47:25 2021 +0200 drm/msm/mdp5: Do not multiply vclk line count by 100 [ Upstream commit 377569f82ea8228c421cef4da33e056a900b58ca ] 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/mdss/mdss_mdp_intf_cmd.c?h=LA.UM.8.6.c26-02400-89xx.0#n288 [2]: https://source.codeaurora.org/quic/la/kernel/msm-3.18/tree/drivers/video/msm/mdss/mdss_dsi_panel.c?h=LA.UM.8.6.c26-02400-89xx.0#n1648 Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxxx> Signed-off-by: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210406214726.131534-3-marijn.suijten@xxxxxxxxxxxxxx Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> 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 288f18cbf62d..0425400f44db 100644 --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cmd_encoder.c +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cmd_encoder.c @@ -41,7 +41,7 @@ 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; @@ -51,8 +51,8 @@ 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; @@ -64,7 +64,7 @@ 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;