[Intel-gfx] [PATCH v4 6/6] drm/i915: fix context/engine cleanup order

[Chris Wilson]

On Fri, Jan 29, 2016 at 07:19:31PM +0000, Dave Gordon wrote:
> From: Nick Hoath <nicholas.hoath at intel.com>
> 
> Swap the order of context & engine cleanup, so that contexts are cleaned
> up first, and *then* engines. This is a more sensible order anyway, but
> in particular has become necessary since the 'intel_ring_initialized()
> must be simple and inline' patch, which now uses ring->dev as an
> 'initialised' flag, so it can now be NULL after engine teardown. This in
> turn can cause a problem in the context code, which (used to) check the
> ring->dev->struct_mutex -- causing a fault if ring->dev was NULL.
> 
> Also rename the cleanup function to reflect what it actually does
> (cleanup engines, not a ringbuffer), and fix an annoying whitespace
> issue.
> 
> v2: Also make the fix in i915_load_modeset_init, not just in
>     i915_driver_unload (Chris Wilson)
> v3: Had extra stuff in it.
> v4: Reverted extra stuff (so we're back to v2).
>     Rebased and updated commentary above (Dave Gordon).
> 
> Signed-off-by: Nick Hoath <nicholas.hoath at intel.com>
> Signed-off-by: David Gordon <david.s.gordon at intel.com>
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Have to drop that, with the recent context changes.

You have to move the gpu-reset now for execlists.

Basically pull it out into:

static void i915_unload_gem(struct drm_device *dev)
{
       /*
        * Neither the BIOS, ourselves or any other kernel
        * expects the system to be in execlists mode on startup,
        * so we need to reset the GPU back to legacy mode. And the only
        * known way to disable logical contexts is through a GPU reset.
        *
        * So in order to leave the system in a known default configration,
        * always reset the GPU upon unload. This also cleans up the GEM
        * state tracking, flushing off the requests and leaving the system
        * idle.
        *
        * Note that is of the upmost importance that the GPU is idle and
        * all stray writes are flushed *before* we dismantle the backing
        * storage for the pinned objects.
        */
       i915_reset(dev);

       mutex_lock(&dev->struct_mutex);
       i915_gem_context_fini(dev);
       i915_gem_cleanup_ringbuffer(dev);
       mutex_unlock(&dev->struct_mutex);
}

and then kill the intel_gpu_reset along both the cleanup pathsh
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre