[PATCH v6 6/7] drm/mediatek: change the dsi phytiming calculate method

[Jitao Shi]

Change the method of frame rate calc which can get more accurate
frame rate.

data rate = pixel_clock * bit_per_pixel / lanes
Adjust hfp_wc to adapt the additional phy_data

if MIPI_DSI_MODE_VIDEO_BURST
	hfp_wc = hfp * bpp - data_phy_cycles * lanes - 12 - 6;
else
	hfp_wc = hfp * bpp - data_phy_cycles * lanes - 12;

Note:
//(2: 1 for sync, 1 for phy idle)
data_phy_cycles = T_hs_exit + T_lpx + T_hs_prepare + T_hs_zero + 2;

bpp: bit per pixel

Signed-off-by: Jitao Shi <jitao.shi@xxxxxxxxxxxx>
Tested-by: Ryan Case <ryandcase@xxxxxxxxxxxx>
---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 118 ++++++++++++++++++++---------
 1 file changed, 81 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index b3676426aeb5..4d98ea08635a 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -136,12 +136,6 @@
 #define DATA_0				(0xff << 16)
 #define DATA_1				(0xff << 24)
 
-#define T_LPX		5
-#define T_HS_PREP	6
-#define T_HS_TRAIL	8
-#define T_HS_EXIT	7
-#define T_HS_ZERO	10
-
 #define NS_TO_CYCLE(n, c)    ((n) / (c) + (((n) % (c)) ? 1 : 0))
 
 #define MTK_DSI_HOST_IS_READ(type) \
@@ -150,6 +144,25 @@
 	(type == MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM) || \
 	(type == MIPI_DSI_DCS_READ))
 
+struct mtk_phy_timing {
+	u32 lpx;
+	u32 da_hs_prepare;
+	u32 da_hs_zero;
+	u32 da_hs_trail;
+
+	u32 ta_go;
+	u32 ta_sure;
+	u32 ta_get;
+	u32 da_hs_exit;
+
+	u32 clk_hs_zero;
+	u32 clk_hs_trail;
+
+	u32 clk_hs_prepare;
+	u32 clk_hs_post;
+	u32 clk_hs_exit;
+};
+
 struct phy;
 
 struct mtk_dsi_driver_data {
@@ -180,6 +193,7 @@ struct mtk_dsi {
 	enum mipi_dsi_pixel_format format;
 	unsigned int lanes;
 	struct videomode vm;
+	struct mtk_phy_timing phy_timing;
 	int refcount;
 	bool enabled;
 	u32 irq_data;
@@ -213,17 +227,36 @@ static void mtk_dsi_phy_timconfig(struct mtk_dsi *dsi)
 {
 	u32 timcon0, timcon1, timcon2, timcon3;
 	u32 ui, cycle_time;
+	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 = 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(90 + 4 * ui, cycle_time);
 
-	ui = 1000 / dsi->data_rate + 0x01;
-	cycle_time = 8000 / dsi->data_rate + 0x01;
+	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;
 
-	timcon0 = T_LPX | T_HS_PREP << 8 | T_HS_ZERO << 16 | T_HS_TRAIL << 24;
-	timcon1 = 4 * T_LPX | (3 * T_LPX / 2) << 8 | 5 * T_LPX << 16 |
-		  T_HS_EXIT << 24;
-	timcon2 = ((NS_TO_CYCLE(0x64, cycle_time) + 0xa) << 24) |
-		  (NS_TO_CYCLE(0x150, cycle_time) << 16);
-	timcon3 = NS_TO_CYCLE(0x40, cycle_time) | (2 * T_LPX) << 16 |
-		  NS_TO_CYCLE(80 + 52 * ui, cycle_time) << 8;
+	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;
+
+	timcon0 = timing->lpx | timing->da_hs_prepare << 8 |
+		  timing->da_hs_zero << 16 | timing->da_hs_trail << 24;
+	timcon1 = timing->ta_go | timing->ta_sure << 8 |
+		  timing->ta_get << 16 | timing->da_hs_exit << 24;
+	timcon2 = 1 << 8 | timing->clk_hs_zero << 16 |
+		  timing->clk_hs_trail << 24;
+	timcon3 = timing->clk_hs_prepare | timing->clk_hs_post << 8 |
+		  timing->clk_hs_exit << 16;
 
 	writel(timcon0, dsi->regs + DSI_PHY_TIMECON0);
 	writel(timcon1, dsi->regs + DSI_PHY_TIMECON1);
@@ -410,7 +443,8 @@ static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi)
 	u32 horizontal_sync_active_byte;
 	u32 horizontal_backporch_byte;
 	u32 horizontal_frontporch_byte;
-	u32 dsi_tmp_buf_bpp;
+	u32 dsi_tmp_buf_bpp, data_phy_cycles;
+	struct mtk_phy_timing *timing = &dsi->phy_timing;
 
 	struct videomode *vm = &dsi->vm;
 
@@ -437,7 +471,34 @@ static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi)
 		horizontal_backporch_byte = ((vm->hback_porch + vm->hsync_len) *
 			dsi_tmp_buf_bpp - 10);
 
-	horizontal_frontporch_byte = (vm->hfront_porch * dsi_tmp_buf_bpp - 12);
+	data_phy_cycles = timing->lpx + timing->da_hs_prepare +
+				  timing->da_hs_zero + timing->da_hs_exit + 2;
+
+	if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST) {
+		if (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;
+		} 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 >
+		    data_phy_cycles * dsi->lanes + 12) {
+			horizontal_frontporch_byte = vm->hfront_porch *
+						     dsi_tmp_buf_bpp -
+						     data_phy_cycles *
+						     dsi->lanes - 12;
+		} else {
+			DRM_WARN("HFP less than d-phy, FPS will under 60Hz\n");
+			horizontal_frontporch_byte = vm->hfront_porch *
+						     dsi_tmp_buf_bpp;
+		}
+	}
 
 	writel(horizontal_sync_active_byte, dsi->regs + DSI_HSA_WC);
 	writel(horizontal_backporch_byte, dsi->regs + DSI_HBP_WC);
@@ -537,8 +598,7 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
 {
 	struct device *dev = dsi->host.dev;
 	int ret;
-	u64 pixel_clock, total_bits;
-	u32 htotal, htotal_bits, bit_per_pixel, overhead_cycles, overhead_bits;
+	u32 bit_per_pixel;
 
 	if (++dsi->refcount != 1)
 		return 0;
@@ -557,24 +617,8 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
 		break;
 	}
 
-	/**
-	 * htotal_time = htotal * byte_per_pixel / num_lanes
-	 * overhead_time = lpx + hs_prepare + hs_zero + hs_trail + hs_exit
-	 * mipi_ratio = (htotal_time + overhead_time) / htotal_time
-	 * data_rate = pixel_clock * bit_per_pixel * mipi_ratio / num_lanes;
-	 */
-	pixel_clock = dsi->vm.pixelclock;
-	htotal = dsi->vm.hactive + dsi->vm.hback_porch + dsi->vm.hfront_porch +
-			dsi->vm.hsync_len;
-	htotal_bits = htotal * bit_per_pixel;
-
-	overhead_cycles = T_LPX + T_HS_PREP + T_HS_ZERO + T_HS_TRAIL +
-			T_HS_EXIT;
-	overhead_bits = overhead_cycles * dsi->lanes * 8;
-	total_bits = htotal_bits + overhead_bits;
-
-	dsi->data_rate = DIV_ROUND_UP_ULL(pixel_clock * total_bits,
-					  htotal * dsi->lanes);
+	dsi->data_rate = DIV_ROUND_UP_ULL(dsi->vm.pixelclock * bit_per_pixel,
+					  dsi->lanes);
 
 	ret = clk_set_rate(dsi->hs_clk, dsi->data_rate);
 	if (ret < 0) {
-- 
2.21.0