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 4f5c733ca9748f212cfb022aaf97e54ce870fdc4..79cc437af3b8f7879f7e60ed4cc842b524d62973 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1954,6 +1954,9 @@ 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;
@@ -4000,7 +4003,7 @@ static void intel_crtc_init(struct drm_device *dev, int pipe)
        }
 
        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;