[Intel-gfx] [PATCH] drm/i915: Also perform gpu reset under execlist mode.

[Chris Wilson]

On Thu, Jun 25, 2015 at 10:40:15PM +0800, bing.niu at intel.com wrote:
> From: "Niu,Bing" <bing.niu at intel.com>
> 
> It is found that i915 will not reset gpu under execlist mode when
> unload module. that will lead to some issues when unload/load module
> with different submission mode. e.g. from execlist mode to ring
> buffer mode via loading/unloading i915. Because HW is not in a reset
> state and registers are not clean under such condition.

Now the reason we have the reset there is to disable writes to the power
context after the memory is released. Your complaint above can easily be
read as the driver is unable to correctly initialisae itself from a
random GPU state, which is a fault in driver initialisation.

Have you observed stray memory writes from the GPU after the module is
unloaded? If not, this would seem to be just a band-aid.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre