drm/i915: Compute DSI PLL parameters during .compute_config()

Compute the DSI PLL parameters during .compute_config() rather than
.pre_pll_enable() so that we can fail gracefully if we can't find
suitable parameters.

In order to do that we need to store the DSI PLL parameters in
pipe_config.

v2: Handle BXT too

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460488478-18311-3-git-send-email-ville.syrjala@linux.intel.com
Tested-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index d9266f9..4cca155 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12763,6 +12763,9 @@
 	PIPE_CONF_CHECK_X(dpll_hw_state.cfgcr1);
 	PIPE_CONF_CHECK_X(dpll_hw_state.cfgcr2);
 
+	PIPE_CONF_CHECK_X(dsi_pll.ctrl);
+	PIPE_CONF_CHECK_X(dsi_pll.div);
+
 	if (IS_G4X(dev) || INTEL_INFO(dev)->gen >= 5)
 		PIPE_CONF_CHECK_I(pipe_bpp);