[Intel-gfx] Do we also need to reset HW when execlist mode is enabled?

[Daniel Vetter]

On Wed, Jun 24, 2015 at 05:41:08AM +0800, Zhi Wang wrote:
> Hi Experts:
> 	Recently we found that when i915 module got unloaded, when we were
> debugging some bugs in XenGT. It would not reset HW under execlist mode.
> I'm not sure if this is an issue. But if we keep loading/unloading
> module with the different submission mode, e.g. from execlist mode to
> ring buffer mode via loading/unloading i915, this should be a corner
> case.... Maybe you can provide some advice, or make sure if we need to
> fix it. :)
> 
> If so, we can submit a patch. :)
> 
> Code:
> void i915_gem_context_fini(struct drm_device *dev)
> {
>         struct drm_i915_private *dev_priv = dev->dev_private;
>         struct intel_context *dctx = dev_priv->ring[RCS].default_context;
>         int i;
> 
>         if (dctx->legacy_hw_ctx.rcs_state) {
>                 /* The only known way to stop the gpu from accessing the
> hw context is
>                  * to reset it. Do this as the very last operation to
> avoid confusing
>                  * other code, leading to spurious errors. */
>                 intel_gpu_reset(dev);  // <------------ Move this one to
> the beginning of the function.

Yeah makes sense, if this fixes up your troubles with module unloading and
execlist.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch