[Intel-gfx] [PATCH] drm/i915: disable_shared_pll doesn't work on pre-gen5

[Chris Wilson]

On Mon, Aug 03, 2015 at 01:09:11PM -0700, Jesse Barnes wrote:
> Looks like
> 
> commit eddfcbcdc27fbecb33bff098967bbdd7ca75bfa6
> Author: Maarten Lankhorst <maarten.lankhorst at 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 at virtuousgeek.org>

This blows up in 4.1 (a BUG_ON during boot causing a hard lockup).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre