drm/nv50: DCB quirk for Dell M6300

Uncertain if this is a weirdo configuration, or a BIOS bug.  If it's not
a BIOS bug, we still don't know how to make it work anyway so ignore a
"conflicting" DCB entry to prevent a display hang.

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

diff --git a/drivers/gpu/drm/nouveau/nouveau_bios.c b/drivers/gpu/drm/nouveau/nouveau_bios.c
index 2e8cdd71a6ecda24ae0b98eaf80a6f11fdba16ed..3e274d57d9bbab53c95a47e7e88d8b23cf025d87 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_bios.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bios.c
@@ -5841,6 +5841,31 @@ void merge_like_dcb_entries(struct drm_device *dev, struct dcb_table *dcb)
        dcb->entries = newentries;
 }
 
+static bool
+apply_dcb_encoder_quirks(struct drm_device *dev, int idx, u32 *conn, u32 *conf)
+{
+       /* Dell Precision M6300
+        *   DCB entry 2: 02025312 00000010
+        *   DCB entry 3: 02026312 00000020
+        *
+        * Identical, except apparently a different connector on a
+        * different SOR link.  Not a clue how we're supposed to know
+        * which one is in use if it even shares an i2c line...
+        *
+        * Ignore the connector on the second SOR link to prevent
+        * nasty problems until this is sorted (assuming it's not a
+        * VBIOS bug).
+        */
+       if ((dev->pdev->device == 0x040d) &&
+           (dev->pdev->subsystem_vendor == 0x1028) &&
+           (dev->pdev->subsystem_device == 0x019b)) {
+               if (*conn == 0x02026312 && *conf == 0x00000020)
+                       return false;
+       }
+
+       return true;
+}
+
 static int
 parse_dcb_table(struct drm_device *dev, struct nvbios *bios, bool twoHeads)
 {
@@ -5974,6 +5999,9 @@ parse_dcb_table(struct drm_device *dev, struct nvbios *bios, bool twoHeads)
                if ((connection & 0x0000000f) == 0x0000000f)
                        continue;
 
+               if (!apply_dcb_encoder_quirks(dev, i, &connection, &config))
+                       continue;
+
                NV_TRACEWARN(dev, "Raw DCB entry %d: %08x %08x\n",
                             dcb->entries, connection, config);