soc/mediatek: dsi: Refactor PHY timing calculation

The PHY timing should be calculated by data rate (Mbps). However for
8173 some values were hard-coded so we want to introduce a new
mtk_phy_timing structure and a weak function mtk_dsi_override_phy_timing
that allows per-SOC customization to apply PHY timings.

BUG=b:80501386,b:117254947
TEST=make -j # board = oak and boots

Change-Id: I1176ca06dda026029ff431aca7f9e21479eed670
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34771
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/soc/mediatek/common/dsi.c

@@ -19,6 +19,7 @@
 #include <delay.h>
 #include <edid.h>
 #include <soc/dsi.h>
+#include <string.h>
 #include <timer.h>
 
 static unsigned int mtk_dsi_get_bits_per_pixel(u32 format)
@@ -64,23 +65,51 @@ static int mtk_dsi_get_data_rate(u32 bits_per_pixel, u32 lanes,
 	return data_rate;
 }
 
-static void mtk_dsi_phy_timconfig(u32 data_rate)
+__weak void mtk_dsi_override_phy_timing(struct mtk_phy_timing *timing)
 {
-	u32 timcon0, timcon1, timcon2, timcon3;
-	u32 cycle_time, ui, lpx;
+	/* Do nothing. */
+}
+
+static void mtk_dsi_phy_timing(int data_rate, struct mtk_phy_timing *phy_timing)
+{
+	u32 cycle_time, ui;
 
 	ui = 1000 / data_rate + 0x01;
 	cycle_time = 8000 / data_rate + 0x01;
-	lpx = 5;
 
-	timcon0 = (8 << 24) | (0xa << 16) | (0x6 << 8) | lpx;
-	timcon1 = (7 << 24) | (5 * lpx << 16) | ((3 * lpx) / 2) << 8 |
-		  (4 * lpx);
-	timcon2 = ((DIV_ROUND_UP(0x64, cycle_time) + 0xa) << 24) |
-		  (DIV_ROUND_UP(0x150, cycle_time) << 16);
-	timcon3 = (2 * lpx) << 16 |
-		  DIV_ROUND_UP(80 + 52 * ui, cycle_time) << 8 |
-		  DIV_ROUND_UP(0x40, cycle_time);
+	memset(phy_timing, 0, sizeof(*phy_timing));
+
+	phy_timing->lpx = DIV_ROUND_UP(60, cycle_time);
+	phy_timing->da_hs_prepare = DIV_ROUND_UP((40 + 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) + 80), cycle_time);
+
+	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;
+
+	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;
+
+	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;
+
+	/* Allow board-specific tuning. */
+	mtk_dsi_override_phy_timing(phy_timing);
+
+	u32 timcon0, timcon1, timcon2, timcon3;
+
+	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;
 
 	write32(&dsi0->dsi_phy_timecon0, timcon0);
 	write32(&dsi0->dsi_phy_timecon1, timcon1);
@@ -219,7 +248,8 @@ int mtk_dsi_init(u32 mode_flags, u32 format, u32 lanes, const struct edid *edid)
 
 	mtk_dsi_configure_mipi_tx(data_rate, lanes);
 	mtk_dsi_reset();
-	mtk_dsi_phy_timconfig(data_rate);
+	struct mtk_phy_timing phy_timing;
+	mtk_dsi_phy_timing(data_rate, &phy_timing);
 	mtk_dsi_rxtx_control(mode_flags, lanes);
 	mtk_dsi_clk_hs_mode_disable();
 	mtk_dsi_config_vdo_timing(mode_flags, format, edid);

src/soc/mediatek/common/include/soc/dsi_common.h

@@ -300,10 +300,33 @@ enum {
 	MIPI_DCS_READ_DDB_CONTINUE	= 0xA8,
 };
 
+struct mtk_phy_timing {
+	u8 lpx;
+	u8 da_hs_prepare;
+	u8 da_hs_zero;
+	u8 da_hs_trail;
+
+	u8 ta_go;
+	u8 ta_sure;
+	u8 ta_get;
+	u8 da_hs_exit;
+
+	u8 da_hs_sync;
+	u8 clk_hs_zero;
+	u8 clk_hs_trail;
+
+	u8 clk_hs_prepare;
+	u8 clk_hs_post;
+	u8 clk_hs_exit;
+};
+
 /* Functions that each SOC should provide. */
 void mtk_dsi_reset(void);
 void mtk_dsi_configure_mipi_tx(int data_rate, u32 lanes);
 
+/* Functions as weak no-ops that can be overridden. */
+void mtk_dsi_override_phy_timing(struct mtk_phy_timing *timing);
+
 /* Public API provided in common/dsi.c */
 int mtk_dsi_init(u32 mode_flags, u32 format, u32 lanes,
 		 const struct edid *edid);

src/soc/mediatek/mt8173/dsi.c

@@ -107,6 +107,23 @@ void mtk_dsi_reset(void)
 	clrbits_le32(&dsi0->dsi_con_ctrl, 1);
 }
 
+void mtk_dsi_override_phy_timing(struct mtk_phy_timing *timing)
+{
+	int lpx = 5;
+	timing->lpx = lpx;
+	timing->da_hs_prepare = 6;
+	timing->da_hs_zero = 10;
+	timing->da_hs_trail = 8;
+
+	timing->ta_go = 4 * lpx;
+	timing->ta_sure = 3 * lpx / 2;
+	timing->ta_get = 5 * lpx;
+	timing->da_hs_exit = 7;
+
+	timing->da_hs_sync = 0;
+	timing->clk_hs_exit = 2 * lpx;
+}
+
 void mtk_dsi_pin_drv_ctrl(void)
 {
 	struct stopwatch sw;