drm/i915: Remove too early plane enable on pre-PCH hardware

Enabling the plane before we have assigned valid address means that it
will access random PTE (often with conflicting memory types) and cause
GPU lockups. However, enabling the plane too early appears to workaround
a number of bugs in our modesetting code.

Cc: Franz Melchior <[email protected]>
References: https://bugs.freedesktop.org/show_bug.cgi?id=39947
References: https://bugs.freedesktop.org/show_bug.cgi?id=41091
References: https://bugs.freedesktop.org/show_bug.cgi?id=49041
Signed-off-by: Chris Wilson <[email protected]>
Acked-by: Jesse Barnes <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index c5f071daa851b20c6ae9ef06f82cc517d818d8bb..cf9dfcd7a94f594a134efa4dc4add488bc940d82 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3932,7 +3932,6 @@ static int i9xx_crtc_mode_set(struct drm_crtc *crtc,
 
        I915_WRITE(DSPCNTR(plane), dspcntr);
        POSTING_READ(DSPCNTR(plane));
-       intel_enable_plane(dev_priv, plane, pipe);
 
        ret = intel_pipe_set_base(crtc, x, y, old_fb);