drm/i915: disable_shared_pll doesn't work on pre-gen5

Looks like

commit eddfcbcdc27fbecb33bff098967bbdd7ca75bfa6
Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date:   Mon Jun 15 12:33:53 2015 +0200
    drm/i915: Update less state during modeset.

introduced the unconditional calling of disable_shared_dpll, but didn't
fix up pre-gen5 to avoid the BUG_ON at the top of the function.

So change the BUG_ON into a gen check (alternately we could move the
BUG_ON until later, since we shouldn't have a pll struct here either,
but this seems clearer to read).

This fixes a crash on load on my x200s platform.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f4ed4f1..9e4ced5 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1936,7 +1936,9 @@ static void intel_disable_shared_dpll(struct intel_crtc *crtc)
        struct intel_shared_dpll *pll = intel_crtc_to_shared_dpll(crtc);
 
        /* PCH only available on ILK+ */
-       BUG_ON(INTEL_INFO(dev)->gen < 5);
+       if (INTEL_INFO(dev)->gen < 5)
+               return;
+
        if (pll == NULL)
                return;