[PATCH] drm/mediatek: reduce the hbp and hfp for phy timing

[Jitao Shi]

There are some extra data transfer in dsi.
ex. LPX, hs_prepare, hs_zero, hs_exit and the sof/eof of dsi packet.
This signal will enlarge the line time. So the real frame on dsi bus
will be lower than calc by video timing.

So dsi driver reduces the hbp and hfp to keep the line time.

Signed-off-by: Jitao Shi <jitao.shi at mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 67 +++++++++++++++++-------------
 1 file changed, 38 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index e9931bbbe846..f247fad47709 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -230,28 +230,25 @@ static void mtk_dsi_mask(struct mtk_dsi *dsi, u32 offset, u32 mask, u32 data)
 static void mtk_dsi_phy_timconfig(struct mtk_dsi *dsi)
 {
 	u32 timcon0, timcon1, timcon2, timcon3;
-	u32 ui, cycle_time;
+	u32 data_rate_mhz = DIV_ROUND_UP(dsi->data_rate, 1000000);
 	struct mtk_phy_timing *timing = &dsi->phy_timing;
 
-	ui = DIV_ROUND_UP(1000000000, dsi->data_rate);
-	cycle_time = div_u64(8000000000ULL, dsi->data_rate);
+	timing->lpx = (60 * data_rate_mhz / (8 * 1000)) + 1;
+	timing->da_hs_prepare = (80 * data_rate_mhz + 4 * 1000) / 8000;
+	timing->da_hs_zero = (170 * data_rate_mhz + 10 * 1000) / 8000 + 1 -
+				 timing->da_hs_prepare;
+	timing->da_hs_trail = timing->da_hs_prepare + 1;
 
-	timing->lpx = NS_TO_CYCLE(60, cycle_time);
-	timing->da_hs_prepare = NS_TO_CYCLE(50 + 5 * ui, cycle_time);
-	timing->da_hs_zero = NS_TO_CYCLE(110 + 6 * ui, cycle_time);
-	timing->da_hs_trail = NS_TO_CYCLE(77 + 4 * ui, cycle_time);
+	timing->ta_go = 4 * timing->lpx - 2;
+	timing->ta_sure = timing->lpx + 2;
+	timing->ta_get = 4 * timing->lpx;
+	timing->da_hs_exit = 2 * timing->lpx + 1;
 
-	timing->ta_go = 4 * timing->lpx;
-	timing->ta_sure = 3 * timing->lpx / 2;
-	timing->ta_get = 5 * timing->lpx;
-	timing->da_hs_exit = 2 * timing->lpx;
-
-	timing->clk_hs_zero = NS_TO_CYCLE(336, cycle_time);
-	timing->clk_hs_trail = NS_TO_CYCLE(100, cycle_time) + 10;
-
-	timing->clk_hs_prepare = NS_TO_CYCLE(64, cycle_time);
-	timing->clk_hs_post = NS_TO_CYCLE(80 + 52 * ui, cycle_time);
-	timing->clk_hs_exit = 2 * timing->lpx;
+	timing->clk_hs_prepare = 70 * data_rate_mhz / (8 * 1000);
+	timing->clk_hs_post = timing->clk_hs_prepare + 8;
+	timing->clk_hs_trail = timing->clk_hs_prepare;
+	timing->clk_hs_zero = timing->clk_hs_trail * 4;
+	timing->clk_hs_exit = 2 * timing->clk_hs_trail;
 
 	timcon0 = timing->lpx | timing->da_hs_prepare << 8 |
 		  timing->da_hs_zero << 16 | timing->da_hs_trail << 24;
@@ -482,27 +479,39 @@ static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi)
 			dsi_tmp_buf_bpp - 10);
 
 	data_phy_cycles = timing->lpx + timing->da_hs_prepare +
-				  timing->da_hs_zero + timing->da_hs_exit + 2;
+				  timing->da_hs_zero + timing->da_hs_exit + 3;
 
 	if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST) {
-		if (vm->hfront_porch * dsi_tmp_buf_bpp >
+		if ((vm->hfront_porch + vm->hback_porch) * dsi_tmp_buf_bpp >
 		    data_phy_cycles * dsi->lanes + 18) {
-			horizontal_frontporch_byte = vm->hfront_porch *
-						     dsi_tmp_buf_bpp -
-						     data_phy_cycles *
-						     dsi->lanes - 18;
+			horizontal_frontporch_byte =
+				vm->hfront_porch * dsi_tmp_buf_bpp -
+				(data_phy_cycles * dsi->lanes + 18) *
+				vm->hfront_porch /
+				(vm->hfront_porch + vm->hback_porch);
+
+			horizontal_backporch_byte =
+				horizontal_backporch_byte -
+				(data_phy_cycles * dsi->lanes + 18) *
+				vm->hback_porch /
+				(vm->hfront_porch + vm->hback_porch);
 		} else {
 			DRM_WARN("HFP less than d-phy, FPS will under 60Hz\n");
 			horizontal_frontporch_byte = vm->hfront_porch *
 						     dsi_tmp_buf_bpp;
 		}
 	} else {
-		if (vm->hfront_porch * dsi_tmp_buf_bpp >
+		if ((vm->hfront_porch + vm->hback_porch) * dsi_tmp_buf_bpp >
 		    data_phy_cycles * dsi->lanes + 12) {
-			horizontal_frontporch_byte = vm->hfront_porch *
-						     dsi_tmp_buf_bpp -
-						     data_phy_cycles *
-						     dsi->lanes - 12;
+			horizontal_frontporch_byte =
+				vm->hfront_porch * dsi_tmp_buf_bpp -
+				(data_phy_cycles * dsi->lanes + 12) *
+				vm->hfront_porch /
+				(vm->hfront_porch + vm->hback_porch);
+			horizontal_backporch_byte = horizontal_backporch_byte -
+				(data_phy_cycles * dsi->lanes + 12) *
+				vm->hback_porch /
+				(vm->hfront_porch + vm->hback_porch);
 		} else {
 			DRM_WARN("HFP less than d-phy, FPS will under 60Hz\n");
 			horizontal_frontporch_byte = vm->hfront_porch *
-- 
2.21.0