[PATCH 20/27] drm/rockchip: dw-mipi-dsi: properly configure PHY timing

[John Keeping]

These values are specified as constant time periods but the PHY
configuration is in terms of the current lane byte clock so using
constant values guarantees that the timings will be outside the
specification with some display configurations.

Derive the necessary configuration from the byte clock in order to
ensure that the PHY configuration is correct.

Signed-off-by: John Keeping <john at metanate.com>
---
 drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 36 ++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
index 61cee02e5f72..911ddcbab00d 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
@@ -384,6 +384,26 @@ static void dw_mipi_dsi_phy_write(struct dw_mipi_dsi *dsi, u8 test_code,
 	dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_TESTCLK | PHY_UNTESTCLR);
 }
 
+/**
+ * ns2bc - Nanoseconds to byte clock cycles
+ */
+static inline unsigned int ns2bc(struct dw_mipi_dsi *dsi, int ns)
+{
+	unsigned long byte_clk_khz = dsi->lane_mbps * MSEC_PER_SEC / 8;
+
+	return (ns * (byte_clk_khz / 1000) + 999) / 1000;
+}
+
+/**
+ * ns2ui - Nanoseconds to UI time periods
+ */
+static inline unsigned int ns2ui(struct dw_mipi_dsi *dsi, int ns)
+{
+	unsigned long byte_clk_khz = dsi->lane_mbps * MSEC_PER_SEC;
+
+	return (ns * (byte_clk_khz / 1000) + 999) / 1000;
+}
+
 static int dw_mipi_dsi_phy_init(struct dw_mipi_dsi *dsi)
 {
 	int ret, testdin, vco, val;
@@ -435,10 +455,18 @@ static int dw_mipi_dsi_phy_init(struct dw_mipi_dsi *dsi)
 					 SETRD_MAX | POWER_MANAGE |
 					 TER_RESISTORS_ON);
 
-
-	dw_mipi_dsi_phy_write(dsi, 0x70, TLP_PROGRAM_EN | 0xf);
-	dw_mipi_dsi_phy_write(dsi, 0x71, THS_PRE_PROGRAM_EN | 0x55);
-	dw_mipi_dsi_phy_write(dsi, 0x72, THS_ZERO_PROGRAM_EN | 0xa);
+	dw_mipi_dsi_phy_write(dsi, 0x60, TLP_PROGRAM_EN | ns2bc(dsi, 500));
+	dw_mipi_dsi_phy_write(dsi, 0x61, THS_PRE_PROGRAM_EN | ns2ui(dsi, 40));
+	dw_mipi_dsi_phy_write(dsi, 0x62, THS_ZERO_PROGRAM_EN | ns2bc(dsi, 300));
+	dw_mipi_dsi_phy_write(dsi, 0x63, THS_PRE_PROGRAM_EN | ns2ui(dsi, 100));
+	dw_mipi_dsi_phy_write(dsi, 0x64, BIT(5) | ns2bc(dsi, 100));
+	dw_mipi_dsi_phy_write(dsi, 0x65, BIT(5) | (ns2bc(dsi, 60) + 7));
+
+	dw_mipi_dsi_phy_write(dsi, 0x70, TLP_PROGRAM_EN | ns2bc(dsi, 500));
+	dw_mipi_dsi_phy_write(dsi, 0x71, THS_PRE_PROGRAM_EN | (ns2ui(dsi, 50) + 5));
+	dw_mipi_dsi_phy_write(dsi, 0x72, THS_ZERO_PROGRAM_EN | (ns2bc(dsi, 140) + 2));
+	dw_mipi_dsi_phy_write(dsi, 0x73, THS_PRE_PROGRAM_EN | (ns2ui(dsi, 60) + 8));
+	dw_mipi_dsi_phy_write(dsi, 0x74, BIT(5) | ns2bc(dsi, 100));
 
 	dsi_write(dsi, DSI_PHY_RSTZ, PHY_ENFORCEPLL | PHY_ENABLECLK |
 				     PHY_UNRSTZ | PHY_UNSHUTDOWNZ);
-- 
2.10.0.278.g4f427b1.dirty