drm/i915/BXT: Get pipe conf from the port registers

At BXT DSI, PIPE registers are inactive. So we can't get the
PIPE's mode parameters from them. The possible option is
retriving them from the PORT registers.

The required changes are added for BXT in intel_dsi_get_config
(encoder->get_config).

v2: Addressed the Jani's comments
    -removed the redundant call to encoder->get_config
    -read bpp from port register
    -removed retrival of src_size from encoder->get_config

v3: pipe_config->pipe_bpp is fixed
    Jani's review comments addressed:
	Few horizontal timing parameters dropped from the patch to make
	progress, as there seems to be some disagreement on
	best/feasible/possible options.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>

Previously Reviewed at: https://lists.freedesktop.org/archives/intel-gfx/2016-April/091737.html
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460019967-26501-2-git-send-email-ramalingam.c@intel.com

drivers/gpu/drm/i915/intel_dsi.c

@@ -758,14 +758,74 @@ out_put_power:
 	return active;
 }
 
+static void bxt_dsi_get_pipe_config(struct intel_encoder *encoder,
+				 struct intel_crtc_state *pipe_config)
+{
+	struct drm_device *dev = encoder->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_display_mode *adjusted_mode =
+					&pipe_config->base.adjusted_mode;
+	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
+	unsigned int bpp, fmt;
+	enum port port;
+	u16 vfp, vsync, vbp;
+
+	/*
+	 * Atleast one port is active as encoder->get_config called only if
+	 * encoder->get_hw_state() returns true.
+	 */
+	for_each_dsi_port(port, intel_dsi->ports) {
+		if (I915_READ(BXT_MIPI_PORT_CTRL(port)) & DPI_ENABLE)
+			break;
+	}
+
+	fmt = I915_READ(MIPI_DSI_FUNC_PRG(port)) & VID_MODE_FORMAT_MASK;
+	pipe_config->pipe_bpp =
+			mipi_dsi_pixel_format_to_bpp(
+				pixel_format_from_register_bits(fmt));
+	bpp = pipe_config->pipe_bpp;
+
+	/* In terms of pixels */
+	adjusted_mode->crtc_hdisplay =
+				I915_READ(BXT_MIPI_TRANS_HACTIVE(port));
+	adjusted_mode->crtc_vdisplay =
+				I915_READ(BXT_MIPI_TRANS_VACTIVE(port));
+	adjusted_mode->crtc_vtotal =
+				I915_READ(BXT_MIPI_TRANS_VTOTAL(port));
+
+	/*
+	 * TODO: Retrieve hfp, hsync and hbp. Adjust them for dual link and
+	 * calculate hsync_start, hsync_end, htotal and hblank_end
+	 */
+
+	/* vertical values are in terms of lines */
+	vfp = I915_READ(MIPI_VFP_COUNT(port));
+	vsync = I915_READ(MIPI_VSYNC_PADDING_COUNT(port));
+	vbp = I915_READ(MIPI_VBP_COUNT(port));
+
+	adjusted_mode->crtc_hblank_start = adjusted_mode->crtc_hdisplay;
+
+	adjusted_mode->crtc_vsync_start =
+				vfp + adjusted_mode->crtc_vdisplay;
+	adjusted_mode->crtc_vsync_end =
+				vsync + adjusted_mode->crtc_vsync_start;
+	adjusted_mode->crtc_vblank_start = adjusted_mode->crtc_vdisplay;
+	adjusted_mode->crtc_vblank_end = adjusted_mode->crtc_vtotal;
+}
+
+
 static void intel_dsi_get_config(struct intel_encoder *encoder,
 				 struct intel_crtc_state *pipe_config)
 {
+	struct drm_device *dev = encoder->base.dev;
 	u32 pclk;
 	DRM_DEBUG_KMS("\n");
 
 	pipe_config->has_dsi_encoder = true;
 
+	if (IS_BROXTON(dev))
+		bxt_dsi_get_pipe_config(encoder, pipe_config);
+
 	/*
 	 * DPLL_MD is not used in case of DSI, reading will get some default value
 	 * set dpll_md = 0