soc/mediatek: dsi: reduce the hbp and hfp for phy timing

The extra data transfer in DSI, namely, lpx, hs_prepare, hs_zero,
hs_exit and the sof/eof of DSI packets, will enlarge the line time,
which causes the real frame on dsi bus to be lower than the one
calculated by video timing. Therefore, hfp_byte is reduced by d_phy to
compensate the increase in time by the extra data transfer. However, if
hfp_byte is not large enough, the hsync period will be increased on DSI
data, leading to display scrolling in firmware screen.

To avoid this situation, this patch changes the DSI Tx driver to reduce
both hfp_byte and hbp_byte, with the amount proportional to hfp and hbp,
respectively. Refer to kernel's change in CL:1915442.

Also rename 'phy_timing' to 'timing' to sync with kernel upstream.

Since the phy timing initialization sequence has been corrected, the m
value adjustment in the analogix driver can be removed.

BUG=b:144824303
BRANCH=kukui
TEST=emerge-jacuzzi coreboot
TEST=Boots and sees firmware screen on krane and juniper
TEST=No scrolling issue on juniper AUO and InnoLux panels

Change-Id: I10a4d8a4fb41c309fa1917cf1cdf19dabed98227
Signed-off-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38400
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>

2 files changed, 49 insertions, 45 deletions

diff --git a/src/drivers/analogix/anx7625/anx7625.c b/src/drivers/analogix/anx7625/anx7625.c
index 293cc1c20e..9387a83bd9 100644
--- a/src/drivers/analogix/anx7625/anx7625.c
+++ b/src/drivers/analogix/anx7625/anx7625.c
@@ -273,7 +273,7 @@ static int anx7625_calculate_m_n(u32 pixelclock,
 		return 1;
 	}
 
-	*m = (unsigned long long)pixelclock * 599 / 600;
+	*m = pixelclock;
 	*n = XTAL_FRQ / post_divider;
 	*pd = post_divider;
 
diff --git a/src/soc/mediatek/common/dsi.c b/src/soc/mediatek/common/dsi.c
index 9222cb0c4b..be99fe8992 100644
--- a/src/soc/mediatek/common/dsi.c
+++ b/src/soc/mediatek/common/dsi.c
@@ -74,47 +74,43 @@ __weak void mtk_dsi_override_phy_timing(struct mtk_phy_timing *timing)
 	/* Do nothing. */
 }
 
-static void mtk_dsi_phy_timing(u32 data_rate, struct mtk_phy_timing *phy_timing)
+static void mtk_dsi_phy_timing(u32 data_rate, struct mtk_phy_timing *timing)
 {
-	u32 cycle_time, ui;
+	u32 timcon0, timcon1, timcon2, timcon3;
 	u32 data_rate_mhz = DIV_ROUND_UP(data_rate, MHz);
 
-	ui = 1000 / data_rate_mhz + 0x01;
-	cycle_time = 8000 / data_rate_mhz + 0x01;
-
-	memset(phy_timing, 0, sizeof(*phy_timing));
+	memset(timing, 0, sizeof(*timing));
 
-	phy_timing->lpx = DIV_ROUND_UP(60, cycle_time);
-	phy_timing->da_hs_prepare = DIV_ROUND_UP((50 + 5 * ui), cycle_time);
-	phy_timing->da_hs_zero = DIV_ROUND_UP((110 + 6 * ui), cycle_time);
-	phy_timing->da_hs_trail = DIV_ROUND_UP(((4 * ui) + 77), cycle_time);
+	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;
 
-	phy_timing->ta_go = 4U * phy_timing->lpx;
-	phy_timing->ta_sure = 3U * phy_timing->lpx / 2U;
-	phy_timing->ta_get = 5U * phy_timing->lpx;
-	phy_timing->da_hs_exit = 2U * phy_timing->lpx;
+	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;
 
-	phy_timing->da_hs_sync = 1;
-	phy_timing->clk_hs_zero = DIV_ROUND_UP(0x150U, cycle_time);
-	phy_timing->clk_hs_trail = DIV_ROUND_UP(0x64U, cycle_time) + 0xaU;
+	timing->da_hs_sync = 1;
 
-	phy_timing->clk_hs_prepare = DIV_ROUND_UP(0x40U, cycle_time);
-	phy_timing->clk_hs_post = DIV_ROUND_UP(80U + 52U * ui, cycle_time);
-	phy_timing->clk_hs_exit = 2U * phy_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;
 
 	/* Allow board-specific tuning. */
-	mtk_dsi_override_phy_timing(phy_timing);
-
-	u32 timcon0, timcon1, timcon2, timcon3;
+	mtk_dsi_override_phy_timing(timing);
 
-	timcon0 = phy_timing->lpx | phy_timing->da_hs_prepare << 8 |
-		  phy_timing->da_hs_zero << 16 | phy_timing->da_hs_trail << 24;
-	timcon1 = phy_timing->ta_go | phy_timing->ta_sure << 8 |
-		  phy_timing->ta_get << 16 | phy_timing->da_hs_exit << 24;
-	timcon2 = phy_timing->da_hs_sync << 8 | phy_timing->clk_hs_zero << 16 |
-		  phy_timing->clk_hs_trail << 24;
-	timcon3 = phy_timing->clk_hs_prepare | phy_timing->clk_hs_post << 8 |
-		  phy_timing->clk_hs_exit << 16;
+	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 = timing->da_hs_sync << 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;
 
 	write32(&dsi0->dsi_phy_timecon0, timcon0);
 	write32(&dsi0->dsi_phy_timecon1, timcon1);
@@ -180,6 +176,8 @@ static void mtk_dsi_config_vdo_timing(u32 mode_flags, u32 format, u32 lanes,
 				      const struct mtk_phy_timing *phy_timing)
 {
 	u32 hsync_active_byte;
+	u32 hbp;
+	u32 hfp;
 	u32 hbp_byte;
 	u32 hfp_byte;
 	u32 vbp_byte;
@@ -199,17 +197,20 @@ static void mtk_dsi_config_vdo_timing(u32 mode_flags, u32 format, u32 lanes,
 	write32(&dsi0->dsi_vfp_nl, vfp_byte);
 	write32(&dsi0->dsi_vact_nl, edid->mode.va);
 
-	unsigned int hspw = 0;
-	if (mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
-		hspw = edid->mode.hspw;
-
-	hbp_byte = (edid->mode.hbl - edid->mode.hso - hspw - edid->mode.hborder)
-			* bytes_per_pixel - 10;
 	hsync_active_byte = edid->mode.hspw * bytes_per_pixel - 10;
-	hfp_byte = (edid->mode.hso - edid->mode.hborder) * bytes_per_pixel;
+
+	hbp = edid->mode.hbl - edid->mode.hso - edid->mode.hspw -
+	      edid->mode.hborder;
+	hfp = edid->mode.hso - edid->mode.hborder;
+
+	if (mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
+		hbp_byte = hbp * bytes_per_pixel - 10;
+	else
+		hbp_byte = (hbp + edid->mode.hspw) * bytes_per_pixel - 10;
+	hfp_byte = hfp * bytes_per_pixel;
 
 	data_phy_cycles = phy_timing->lpx + phy_timing->da_hs_prepare +
-		phy_timing->da_hs_zero + phy_timing->da_hs_exit + 2;
+			  phy_timing->da_hs_zero + phy_timing->da_hs_exit + 3;
 
 	u32 delta = 12;
 	if (mode_flags & MIPI_DSI_MODE_VIDEO_BURST)
@@ -218,11 +219,14 @@ static void mtk_dsi_config_vdo_timing(u32 mode_flags, u32 format, u32 lanes,
 	u32 d_phy = phy_timing->d_phy;
 	if (d_phy == 0)
 		d_phy = data_phy_cycles * lanes + delta;
-	if (hfp_byte > d_phy)
-		hfp_byte -= d_phy;
-	else
-		printk(BIOS_ERR, "HFP is not greater than d-phy, FPS < 60Hz "
-		       "and the panel may not work properly.\n");
+
+	if ((hfp + hbp) * bytes_per_pixel > d_phy) {
+		hfp_byte -= d_phy * hfp / (hfp + hbp);
+		hbp_byte -= d_phy * hbp / (hfp + hbp);
+	} else {
+		printk(BIOS_ERR, "HFP plus HBP is not greater than d_phy, "
+		       "the panel may not work properly.\n");
+	}
 
 	write32(&dsi0->dsi_hsa_wc, hsync_active_byte);
 	write32(&dsi0->dsi_hbp_wc, hbp_byte);