drm/i915/dsi: Add check for periodic command mode

If the GOP has programmed periodic command mode,
we need to disable that which would need a
deconfigure and configure sequence.

v2: Fix sparse error, pass only intel_dsi (Jani)
v3: Use intel_de_read

Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200312053841.2794-5-vandita.kulkarni@intel.com

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

@@ -1423,6 +1423,22 @@ static void gen11_dsi_get_timings(struct intel_encoder *encoder,
 	adjusted_mode->crtc_vblank_end = adjusted_mode->crtc_vtotal;
 }
 
+static bool gen11_dsi_is_periodic_cmd_mode(struct intel_dsi *intel_dsi)
+{
+	struct drm_device *dev = intel_dsi->base.base.dev;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	enum transcoder dsi_trans;
+	u32 val;
+
+	if (intel_dsi->ports == BIT(PORT_B))
+		dsi_trans = TRANSCODER_DSI_1;
+	else
+		dsi_trans = TRANSCODER_DSI_0;
+
+	val = intel_de_read(dev_priv, DSI_TRANS_FUNC_CONF(dsi_trans));
+	return (val & DSI_PERIODIC_FRAME_UPDATE_ENABLE);
+}
+
 static void gen11_dsi_get_config(struct intel_encoder *encoder,
 				 struct intel_crtc_state *pipe_config)
 {
@@ -1443,6 +1459,10 @@ static void gen11_dsi_get_config(struct intel_encoder *encoder,
 	gen11_dsi_get_timings(encoder, pipe_config);
 	pipe_config->output_types |= BIT(INTEL_OUTPUT_DSI);
 	pipe_config->pipe_bpp = bdw_get_pipemisc_bpp(crtc);
+
+	if (gen11_dsi_is_periodic_cmd_mode(intel_dsi))
+		pipe_config->hw.adjusted_mode.private_flags |=
+					I915_MODE_FLAG_DSI_PERIODIC_CMD_MODE;
 }
 
 static int gen11_dsi_dsc_compute_config(struct intel_encoder *encoder,
@@ -1526,6 +1546,10 @@ static int gen11_dsi_compute_config(struct intel_encoder *encoder,
 
 	pipe_config->port_clock = afe_clk(encoder, pipe_config) / 5;
 
+	/* We would not operate in periodic command mode */
+	pipe_config->hw.adjusted_mode.private_flags &=
+					~I915_MODE_FLAG_DSI_PERIODIC_CMD_MODE;
+
 	return 0;
 }