Current driver is calculating hbp maximum value by subtracting hsync_start with hdisplay which is front porch value, but the hbp refers to back porch. Back porch value is calculating by subtracting htotal with hsync_end as per drm_mode timings, and BSP code from BPI-M64-bsp is eventually following the same. BPI-M64-bsp is computing hbp as (in drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c) dsi_hbp = (hbp-hspw)*dsi_pixel_bits[format]/8 - (4+2); => (panel->lcd_hbp - timmings->hor_sync_time) => (timmings->hor_back_porch + timmings->hor_sync_time - timmings->hor_sync_time) => timmings->hor_back_porch => mode->htotal - mode->hsync_end So, update the MIPI-DSI hbp value accordingly. Tested on 2-lane, 4-lane DSI LCD panels. Signed-off-by: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx> Tested-by: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx> --- Changes for v3: - Fixed proper commit message - add tested credit Changes for v2: - none drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c index 6bece492b1f7..78bad71045ca 100644 --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c @@ -482,7 +482,7 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi, */ #define HBP_PACKET_OVERHEAD 6 hbp = max((unsigned int)HBP_PACKET_OVERHEAD, - (mode->hsync_start - mode->hdisplay) * Bpp - HBP_PACKET_OVERHEAD); + (mode->htotal - mode->hsync_end) * Bpp - HBP_PACKET_OVERHEAD); /* * The frontporch is set using a blanking packet (4 bytes + -- 2.18.0.321.gffc6fa0e3
