From 294b3810059588aa9459b9125a6b080c76cd19b3 Mon Sep 17 00:00:00 2001 From: Jonathan Marek <jonathan@marek.ca> Date: Thu, 30 May 2024 13:56:50 +0800 Subject: [PATCH] drm/msm/dsi: add a comment to explain pkt_per_line encoding Make it clear why the pkt_per_line value is being "divided by 2". Signed-off-by: Jonathan Marek <jonathan@marek.ca> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> Signed-off-by: Jun Nie <jun.nie@linaro.org> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-QRD Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-HDK Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com> Patchwork: https://patchwork.freedesktop.org/patch/596236/ Link: https://lore.kernel.org/r/20240530-msm-drm-dsc-dsi-video-upstream-4-v6-6-2ab1d334c657@linaro.org Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> --- drivers/gpu/drm/msm/dsi/dsi_host.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index 7252d36687e6..4768cff08381 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -885,7 +885,11 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod /* DSI_VIDEO_COMPRESSION_MODE & DSI_COMMAND_COMPRESSION_MODE * registers have similar offsets, so for below common code use * DSI_VIDEO_COMPRESSION_MODE_XXXX for setting bits + * + * pkt_per_line is log2 encoded, >>1 works for supported values (1,2,4) */ + if (pkt_per_line > 4) + drm_warn_once(msm_host->dev, "pkt_per_line too big"); reg |= DSI_VIDEO_COMPRESSION_MODE_CTRL_PKT_PER_LINE(pkt_per_line >> 1); reg |= DSI_VIDEO_COMPRESSION_MODE_CTRL_EOL_BYTE_NUM(eol_byte_num); reg |= DSI_VIDEO_COMPRESSION_MODE_CTRL_EN; -- GitLab