drm/i915: Prevent double dpms on

commit 032d2a0d068b0368296a56469761394ef03207c3 upstream.

Arguably this is a bug in drm-core in that we should not be called twice
in succession with DPMS_ON, however this is still occuring and we see
FDI link training failures on the second call leading to the occassional
blank display. For the time being ignore the repeated call.

Original patch by Dave Airlie <airlied@redhat.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e9a4b125d66e42db4ed0fcabed689ee4b4a9e6ab..18f317f1dd0122da1e89bee88a3af7f1518b4bdd 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2314,6 +2314,9 @@ static void intel_crtc_dpms(struct drm_crtc *crtc, int mode)
        int pipe = intel_crtc->pipe;
        bool enabled;
 
+       if (intel_crtc->dpms_mode == mode)
+               return;
+
        dev_priv->display.dpms(crtc, mode);
 
        intel_crtc->dpms_mode = mode;
@@ -4915,7 +4918,7 @@ static void intel_crtc_init(struct drm_device *dev, int pipe)
        dev_priv->pipe_to_crtc_mapping[intel_crtc->pipe] = &intel_crtc->base;
 
        intel_crtc->cursor_addr = 0;
-       intel_crtc->dpms_mode = DRM_MODE_DPMS_OFF;
+       intel_crtc->dpms_mode = -1;
        drm_crtc_helper_add(&intel_crtc->base, &intel_helper_funcs);
 
        intel_crtc->busy = false;