drm/nouveau: Workaround missing GPIO tables on an Apple iMac G4 NV18.

This should fix the reported TV-out load detection false positives
(fdo bug 29455).

Reported-by: Vlado Plaga <rechner@vlado-do.de>
Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_bios.c b/drivers/gpu/drm/nouveau/nouveau_bios.c
index 9e7fc1d0321c..e144f7a38d81 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bios.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bios.c
@@ -5807,6 +5807,22 @@ parse_dcb_gpio_table(struct nvbios *bios)
                         gpio->line = tvdac_gpio[1] >> 4;
                         gpio->invert = tvdac_gpio[0] & 2;
                 }
+        } else {
+                /*
+                 * No systematic way to store GPIO info on pre-v2.2
+                 * DCBs, try to match the PCI device IDs.
+                 */
+
+                /* Apple iMac G4 NV18 */
+                if (dev->pdev->device == 0x0189 &&
+                    dev->pdev->subsystem_vendor == 0x10de &&
+                    dev->pdev->subsystem_device == 0x0010) {
+                        struct dcb_gpio_entry *gpio = new_gpio_entry(bios);
+
+                        gpio->tag = DCB_GPIO_TVDAC0;
+                        gpio->line = 4;
+                }
+
         }
 
         if (!gpio_table_ptr)