drm/i915/icl: Add DSI encoder compute config hook

This patch implements compute config for Gen11 DSI encoder which is
required at the time of modeset.

For DSI 8X clock is AFE clock which is 5 times port clock.

v2 by Jani:
 - drop the enable nop hook
 - fixed_mode is always true
 - HAS_GMCH_DISPLAY() is always false

v3 by Jani:
 - set encoder->compute_config dropped during rebase

v4 by Jani:
 - squash Vandita's port clock patch
 - remove todo comment
Co-developed-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: Madhav Chauhan <madhav.chauhan@intel.com>
Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a21574173caa5e2932d9e3c537b0931097ab5ac2.1543500286.git.jani.nikula@intel.com

drivers/gpu/drm/i915/icl_dsi.c

@@ -1074,6 +1074,36 @@ static void gen11_dsi_get_config(struct intel_encoder *encoder,
 	pipe_config->output_types |= BIT(INTEL_OUTPUT_DSI);
 }
 
+static bool gen11_dsi_compute_config(struct intel_encoder *encoder,
+				     struct intel_crtc_state *pipe_config,
+				     struct drm_connector_state *conn_state)
+{
+	struct intel_dsi *intel_dsi = container_of(encoder, struct intel_dsi,
+						   base);
+	struct intel_connector *intel_connector = intel_dsi->attached_connector;
+	struct intel_crtc *crtc = to_intel_crtc(pipe_config->base.crtc);
+	const struct drm_display_mode *fixed_mode =
+					intel_connector->panel.fixed_mode;
+	struct drm_display_mode *adjusted_mode =
+					&pipe_config->base.adjusted_mode;
+
+	intel_fixed_panel_mode(fixed_mode, adjusted_mode);
+	intel_pch_panel_fitting(crtc, pipe_config, conn_state->scaling_mode);
+
+	adjusted_mode->flags = 0;
+
+	/* Dual link goes to trancoder DSI'0' */
+	if (intel_dsi->ports == BIT(PORT_B))
+		pipe_config->cpu_transcoder = TRANSCODER_DSI_1;
+	else
+		pipe_config->cpu_transcoder = TRANSCODER_DSI_0;
+
+	pipe_config->clock_set = true;
+	pipe_config->port_clock = intel_dsi_bitrate(intel_dsi) / 5;
+
+	return true;
+}
+
 static u64 gen11_dsi_get_power_domains(struct intel_encoder *encoder,
 				       struct intel_crtc_state *crtc_state)
 {
@@ -1244,6 +1274,7 @@ void icl_dsi_init(struct drm_i915_private *dev_priv)
 	encoder->disable = gen11_dsi_disable;
 	encoder->port = port;
 	encoder->get_config = gen11_dsi_get_config;
+	encoder->compute_config = gen11_dsi_compute_config;
 	encoder->get_hw_state = gen11_dsi_get_hw_state;
 	encoder->type = INTEL_OUTPUT_DSI;
 	encoder->cloneable = 0;