drm/nouveau: assume no nv04 board has a DCB table

There's a report of a TNT2 where the DCB table pointer is *not* NULL
(it contains a part of a VBIOS data string), and we assume this means
a DCB table is present, causing all kinds of hilarity.

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 9710e69..9dd2efa 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_bios.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bios.c
@@ -5523,11 +5523,13 @@ void merge_like_dcb_entries(struct drm_device *dev, struct parsed_dcb *dcb)
        dcb->entries = newentries;
 }
 
-static int parse_dcb_table(struct drm_device *dev, struct nvbios *bios, bool twoHeads)
+static int
+parse_dcb_table(struct drm_device *dev, struct nvbios *bios, bool twoHeads)
 {
+       struct drm_nouveau_private *dev_priv = dev->dev_private;
        struct bios_parsed_dcb *bdcb = &bios->bdcb;
        struct parsed_dcb *dcb;
-       uint16_t dcbptr, i2ctabptr = 0;
+       uint16_t dcbptr = 0, i2ctabptr = 0;
        uint8_t *dcbtable;
        uint8_t headerlen = 0x4, entries = DCB_MAX_NUM_ENTRIES;
        bool configblock = true;
@@ -5538,16 +5540,18 @@ static int parse_dcb_table(struct drm_device *dev, struct nvbios *bios, bool two
        dcb->entries = 0;
 
        /* get the offset from 0x36 */
-       dcbptr = ROM16(bios->data[0x36]);
+       if (dev_priv->card_type > NV_04) {
+               dcbptr = ROM16(bios->data[0x36]);
+               if (dcbptr == 0x0000)
+                       NV_WARN(dev, "No output data (DCB) found in BIOS\n");
+       }
 
+       /* this situation likely means a really old card, pre DCB */
        if (dcbptr == 0x0) {
-               NV_WARN(dev, "No output data (DCB) found in BIOS, "
-                              "assuming a CRT output exists\n");
-               /* this situation likely means a really old card, pre DCB */
+               NV_INFO(dev, "Assuming a CRT output exists\n");
                fabricate_vga_output(dcb, LEGACY_I2C_CRT, 1);
 
-               if (nv04_tv_identify(dev,
-                                    bios->legacy.i2c_indices.tv) >= 0)
+               if (nv04_tv_identify(dev, bios->legacy.i2c_indices.tv) >= 0)
                        fabricate_tv_output(dcb, twoHeads);
 
                return 0;