Current driver is calculating hfp maximum value by subtracting htotal with hsync_end which is front back value, but the hpp refers to front porch.
Front porch value is calculating by subtracting hsync_start with hdisplay as per drm_mode timings, and BSP code from BPI-M64-bsp is eventually following the same.
BPI-M64-bsp is computing hfp as (from linux-sunxi/ drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
dsi_hbp = (hbp-hspw)*dsi_pixel_bits[format]/8 - (4+2); dsi_hact = x * dsi_pixel_bits[format]/8; dsi_hblk = (ht-hspw)*dsi_pixel_bits[format]/8-(4+4+2); dsi_hfp = dsi_hblk - (4+dsi_hact+2) - (4+dsi_hbp+2);
Example, u32 fmt = dsi_pixel_bits[format]/8; => ((ht-hspw)*fmt - 10) - (6 + x * fmt) - (6 + (hbp-hspw)*fmt - 6) => (ht - hspw - x - (hbp - hspw)) * fmt - 16 => (ht - x - hbp) * fmt - 16 => (ht - x - (timmings->hor_total_time - timmings->hor_front_porch - x) * fmt - 16 => (timmings->hor_total_time - x - timmings->hor_total_time + timmings->hor_front_porch + x) * fmt - 16 => timmings->hor_front_porch * fmt - 16
So, update the DSI hfp timing accordingly.
Tested on 2-lane, 4-lane MIPI-DSI LCD panels.
Signed-off-by: Jagan Teki jagan@amarulasolutions.com --- drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c index 07eba9ec469b..d8947be92f9d 100644 --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c @@ -490,7 +490,8 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi, */ #define HFP_PACKET_OVERHEAD 6 hfp = max((unsigned int)HFP_PACKET_OVERHEAD, - (mode->htotal - mode->hsync_end) * Bpp - HFP_PACKET_OVERHEAD); + (mode->hsync_start - mode->hdisplay) * Bpp - + HFP_PACKET_OVERHEAD);
/* * hblk seems to be the line + porches length.