drm/i915/dsi: separate clock and data lane prepare timing

The history of why the max of VBT clock and data lane prepare timing
parameter is used for both instead of each individually is
unknown. Separate them to follow what the Windows driver does.

Cc; William Tseng <william.tseng@intel.com>

Reviewed-by: William Tseng <william.tseng@intel.com>
Tested-by: William Tseng <william.tseng@intel.com>
Link: https://lore.kernel.org/r/079a26d0aae79f299aee0397dad2d6519cd55071.1743682608.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Author: jnikula

drivers/gpu/drm/i915/display/icl_dsi.c

@@ -1842,23 +1842,20 @@ static void icl_dphy_param_init(struct intel_dsi *intel_dsi)
 	struct mipi_config *mipi_config = connector->panel.vbt.dsi.config;
 	u32 tlpx_ns;
 	u32 prepare_cnt, exit_zero_cnt, clk_zero_cnt;
-	u32 ths_prepare_ns;
+	u32 ths_prepare_esc_clk;
 	u32 hs_zero_cnt;
 	u32 tclk_pre_cnt;
 
 	tlpx_ns = intel_dsi_tlpx_ns(intel_dsi);
 
-	ths_prepare_ns = max(mipi_config->ths_prepare,
-			     mipi_config->tclk_prepare);
-
 	/*
 	 * prepare cnt in escape clocks
 	 * this field represents a hexadecimal value with a precision
 	 * of 1.2 – i.e. the most significant bit is the integer
 	 * and the least significant 2 bits are fraction bits.
 	 * so, the field can represent a range of 0.25 to 1.75
 	 */
-	prepare_cnt = DIV_ROUND_UP(ths_prepare_ns * 4, tlpx_ns);
+	prepare_cnt = DIV_ROUND_UP(mipi_config->tclk_prepare * 4, tlpx_ns);
 	if (prepare_cnt > ICL_PREPARE_CNT_MAX) {
 		drm_dbg_kms(display->drm, "prepare_cnt out of range (%d)\n",
 			    prepare_cnt);
@@ -1867,7 +1864,7 @@ static void icl_dphy_param_init(struct intel_dsi *intel_dsi)
 
 	/* clk zero count in escape clocks */
 	clk_zero_cnt = DIV_ROUND_UP(mipi_config->tclk_prepare_clkzero -
-				    ths_prepare_ns, tlpx_ns);
+				    mipi_config->tclk_prepare, tlpx_ns);
 	if (clk_zero_cnt > ICL_CLK_ZERO_CNT_MAX) {
 		drm_dbg_kms(display->drm,
 			    "clk_zero_cnt out of range (%d)\n", clk_zero_cnt);
@@ -1882,9 +1879,12 @@ static void icl_dphy_param_init(struct intel_dsi *intel_dsi)
 		tclk_pre_cnt = ICL_TCLK_PRE_CNT_MAX;
 	}
 
+	ths_prepare_esc_clk = DIV_ROUND_UP(mipi_config->ths_prepare * 4, tlpx_ns);
+	ths_prepare_esc_clk = min(ths_prepare_esc_clk, 7);
+
 	/* hs zero cnt in escape clocks */
 	hs_zero_cnt = DIV_ROUND_UP(mipi_config->ths_prepare_hszero -
-				   ths_prepare_ns, tlpx_ns);
+				   mipi_config->ths_prepare, tlpx_ns);
 	if (hs_zero_cnt > ICL_HS_ZERO_CNT_MAX) {
 		drm_dbg_kms(display->drm, "hs_zero_cnt out of range (%d)\n",
 			    hs_zero_cnt);
@@ -1910,7 +1910,7 @@ static void icl_dphy_param_init(struct intel_dsi *intel_dsi)
 
 	/* data lanes dphy timings */
 	intel_dsi->dphy_data_lane_reg = (HS_PREPARE_OVERRIDE |
-					 HS_PREPARE(prepare_cnt) |
+					 HS_PREPARE(ths_prepare_esc_clk) |
 					 HS_ZERO_OVERRIDE |
 					 HS_ZERO(hs_zero_cnt) |
 					 HS_EXIT_OVERRIDE |