drm/nouveau/disp/nv04-nv40: abort scanoutpos query on vga analog.

commit e291af3f2259e9e105dfd72416fd5796513791a4 upstream.

nv04_disp_scanoutpos() must abort to trigger simple timestamping
fallback if vtotal/htotal regs return zero. This happens if the
output isn't a digital output, but a vga analog output, as the
regs don't get initialized in that case.

Fixes timestamping failure on nv-40 and earlier with vga output.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/nouveau/core/engine/disp/nv04.c b/drivers/gpu/drm/nouveau/core/engine/disp/nv04.c
index 7cf8b13..6fdf6e3 100644 (file)
--- a/drivers/gpu/drm/nouveau/core/engine/disp/nv04.c
+++ b/drivers/gpu/drm/nouveau/core/engine/disp/nv04.c
@@ -51,6 +51,14 @@ nv04_disp_scanoutpos(struct nouveau_object *object, u32 mthd,
        args->htotal  = nv_rd32(priv, 0x680824 + (head * 0x2000)) & 0xffff;
        args->hblanke = args->htotal - 1;
 
+       /*
+        * If output is vga instead of digital then vtotal/htotal is invalid
+        * so we have to give up and trigger the timestamping fallback in the
+        * drm core.
+        */
+       if (!args->vtotal || !args->htotal)
+               return -ENOTSUPP;
+
        args->time[0] = ktime_to_ns(ktime_get());
        line = nv_rd32(priv, 0x600868 + (head * 0x2000));
        args->time[1] = ktime_to_ns(ktime_get());