Video start delay can be computed by subtracting total vertical timing with front porch timing and with adding 1 delay line for TCON.
BSP code form BPI-M64-bsp is computing video start delay as (in linux-sunxi/drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
u32 vfp = panel->lcd_vt - panel->lcd_y - panel->lcd_vbp; => (panel->lcd_vt) - panel->lcd_y - (panel->lcd_vbp) => (timmings->ver_front_porch + panel->lcd_vbp + panel->lcd_y) - panel->lcd_y - (panel->lcd_vbp) => timmings->ver_front_porch + panel->lcd_vbp + panel->lcd_y - panel->lcd_y - panel->lcd_vbp => timmings->ver_front_porch
So, update the start delay computation accordingly.
Signed-off-by: Jagan Teki jagan@amarulasolutions.com Tested-by: Jagan Teki jagan@amarulasolutions.com --- Changes for v3: - Fixed proper commit message - add tested credit Changes for v2: - none
drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c index 8d154cf2e6d6..6bece492b1f7 100644 --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c @@ -358,7 +358,17 @@ static void sun6i_dsi_inst_init(struct sun6i_dsi *dsi, static u16 sun6i_dsi_get_video_start_delay(struct sun6i_dsi *dsi, struct drm_display_mode *mode) { - return mode->vtotal - (mode->vsync_end - mode->vdisplay) + 1; + u32 vfp = mode->vsync_start - mode->vdisplay; + u32 start_delay; + + start_delay = mode->vtotal - vfp + 1; + if (start_delay > mode->vtotal) + start_delay -= mode->vtotal; + + if (!start_delay) + start_delay = 1; + + return start_delay; }
static void sun6i_dsi_setup_burst(struct sun6i_dsi *dsi,