drm/nouveau: determine a value for display_info.bpc if edid doesn't

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 5e830a5855389ff9c3bc4e98e310fda80bc10a3a..fc42ea8503cb2b6e9b2828231b49adb63da3e9f1 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -644,6 +644,46 @@ nouveau_connector_scaler_modes_add(struct drm_connector *connector)
        return modes;
 }
 
+static void
+nouveau_connector_detect_depth(struct drm_connector *connector)
+{
+       struct drm_nouveau_private *dev_priv = connector->dev->dev_private;
+       struct nouveau_connector *nv_connector = nouveau_connector(connector);
+       struct nouveau_encoder *nv_encoder = nv_connector->detected_encoder;
+       struct nvbios *bios = &dev_priv->vbios;
+       struct drm_display_mode *mode = nv_connector->native_mode;
+       bool duallink;
+
+       /* if the edid is feeling nice enough to provide this info, use it */
+       if (nv_connector->edid && connector->display_info.bpc)
+               return;
+
+       /* if not, we're out of options unless we're LVDS, default to 6bpc */
+       connector->display_info.bpc = 6;
+       if (nv_encoder->dcb->type != OUTPUT_LVDS)
+               return;
+
+       /* LVDS: panel straps */
+       if (bios->fp_no_ddc) {
+               if (bios->fp.if_is_24bit)
+                       connector->display_info.bpc = 8;
+               return;
+       }
+
+       /* LVDS: DDC panel, need to first determine the number of links to
+        * know which if_is_24bit flag to check...
+        */
+       if (nv_connector->edid &&
+           nv_connector->dcb->type == DCB_CONNECTOR_LVDS_SPWG)
+               duallink = ((u8 *)nv_connector->edid)[121] == 2;
+       else
+               duallink = mode->clock >= bios->fp.duallink_transition_clk;
+
+       if ((!duallink && (bios->fp.strapless_is_24bit & 1)) ||
+           ( duallink && (bios->fp.strapless_is_24bit & 2)))
+               connector->display_info.bpc = 8;
+}
+
 static int
 nouveau_connector_get_modes(struct drm_connector *connector)
 {
@@ -688,6 +728,12 @@ nouveau_connector_get_modes(struct drm_connector *connector)
                ret = 1;
        }
 
+       /* Attempt to determine display colour depth, this has to happen after
+        * we've determined the "native" mode for LVDS, as the VBIOS tables
+        * require us to compare against a pixel clock in some cases..
+        */
+       nouveau_connector_detect_depth(connector);
+
        if (nv_encoder->dcb->type == OUTPUT_TV)
                ret = get_slave_funcs(encoder)->get_modes(encoder, connector);