drm/i915: Add support for port enable/disable for dual link configuration

For Dual Link MIPI Panels, both Port A and Port C should be enabled
during the MIPI encoder enabling sequence. Similarly, during the
disabling sequence, both ports needs to be disabled.

v2: Used for_each_dsi_port macro instead of for loop

v3: Used intel_dsi->ports instead of dual_link var for dual link configuration check

v4: Masking of the required MIPI port bits before writing proper values
Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -6665,6 +6665,7 @@ enum punit_power_well {
 #define  DPI_ENABLE					(1 << 31) /* A + C */
 #define  MIPIA_MIPI4DPHY_DELAY_COUNT_SHIFT		27
 #define  MIPIA_MIPI4DPHY_DELAY_COUNT_MASK		(0xf << 27)
+#define  DUAL_LINK_MODE_SHIFT				26
 #define  DUAL_LINK_MODE_MASK				(1 << 26)
 #define  DUAL_LINK_MODE_FRONT_BACK			(0 << 26)
 #define  DUAL_LINK_MODE_PIXEL_ALTERNATIVE		(1 << 26)

drivers/gpu/drm/i915/intel_dsi.c

@@ -108,28 +108,41 @@ static void intel_dsi_port_enable(struct intel_encoder *encoder)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_crtc *intel_crtc = to_intel_crtc(encoder->base.crtc);
 	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
-	enum port port = intel_dsi_pipe_to_port(intel_crtc->pipe);
+	enum port port;
 	u32 temp;
 
-	/* assert ip_tg_enable signal */
-	temp = I915_READ(MIPI_PORT_CTRL(port)) & ~LANE_CONFIGURATION_MASK;
-	temp = temp | intel_dsi->port_bits;
-	I915_WRITE(MIPI_PORT_CTRL(port), temp | DPI_ENABLE);
-	POSTING_READ(MIPI_PORT_CTRL(port));
+	for_each_dsi_port(port, intel_dsi->ports) {
+		temp = I915_READ(MIPI_PORT_CTRL(port));
+		temp &= ~LANE_CONFIGURATION_MASK;
+		temp &= ~DUAL_LINK_MODE_MASK;
+
+		if (intel_dsi->ports == ((1 << PORT_A) | (1 << PORT_C))) {
+			temp |= (intel_dsi->dual_link - 1)
+						<< DUAL_LINK_MODE_SHIFT;
+			temp |= intel_crtc->pipe ?
+					LANE_CONFIGURATION_DUAL_LINK_B :
+					LANE_CONFIGURATION_DUAL_LINK_A;
+		}
+		/* assert ip_tg_enable signal */
+		I915_WRITE(MIPI_PORT_CTRL(port), temp | DPI_ENABLE);
+		POSTING_READ(MIPI_PORT_CTRL(port));
+	}
 }
 
 static void intel_dsi_port_disable(struct intel_encoder *encoder)
 {
 	struct drm_device *dev = encoder->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct intel_crtc *intel_crtc = to_intel_crtc(encoder->base.crtc);
-	enum port port = intel_dsi_pipe_to_port(intel_crtc->pipe);
+	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
+	enum port port;
 	u32 temp;
 
-	/* de-assert ip_tg_enable signal */
-	temp = I915_READ(MIPI_PORT_CTRL(port));
-	I915_WRITE(MIPI_PORT_CTRL(port), temp & ~DPI_ENABLE);
-	POSTING_READ(MIPI_PORT_CTRL(port));
+	for_each_dsi_port(port, intel_dsi->ports) {
+		/* de-assert ip_tg_enable signal */
+		temp = I915_READ(MIPI_PORT_CTRL(port));
+		I915_WRITE(MIPI_PORT_CTRL(port), temp & ~DPI_ENABLE);
+		POSTING_READ(MIPI_PORT_CTRL(port));
+	}
 }
 
 static void intel_dsi_device_ready(struct intel_encoder *encoder)

drivers/gpu/drm/i915/intel_dsi.h

@@ -104,6 +104,7 @@ struct intel_dsi {
 	u8 clock_stop;
 
 	u8 escape_clk_div;
+	u8 dual_link;
 	u32 port_bits;
 	u32 bw_timer;
 	u32 dphy_reg;

drivers/gpu/drm/i915/intel_dsi_panel_vbt.c

@@ -287,6 +287,10 @@ static bool generic_init(struct intel_dsi_device *dsi)
 	intel_dsi->clock_stop = mipi_config->enable_clk_stop ? 1 : 0;
 	intel_dsi->lane_count = mipi_config->lane_cnt + 1;
 	intel_dsi->pixel_format = mipi_config->videomode_color_format << 7;
+	intel_dsi->dual_link = mipi_config->dual_link;
+
+	if (intel_dsi->dual_link)
+		intel_dsi->ports = ((1 << PORT_A) | (1 << PORT_C));
 
 	if (intel_dsi->pixel_format == VID_MODE_FORMAT_RGB666)
 		bits_per_pixel = 18;