[Intel-gfx] [PATCH 1/7] drm/i915: Convert requests to use struct fence

[Jesse Barnes]

On 01/11/2016 11:03 AM, John Harrison wrote:
> On 08/01/2016 21:59, Chris Wilson wrote:
>> On Fri, Jan 08, 2016 at 06:47:22PM +0000, John.C.Harrison at Intel.com wrote:
>>> From: John Harrison <John.C.Harrison at Intel.com>
>>>
>>> There is a construct in the linux kernel called 'struct fence' that is
>>> intended to keep track of work that is executed on hardware. I.e. it
>>> solves the basic problem that the drivers 'struct
>>> drm_i915_gem_request' is trying to address. The request structure does
>>> quite a lot more than simply track the execution progress so is very
>>> definitely still required. However, the basic completion status side
>>> could be updated to use the ready made fence implementation and gain
>>> all the advantages that provides.
>>>
>>> This patch makes the first step of integrating a struct fence into the
>>> request. It replaces the explicit reference count with that of the
>>> fence. It also replaces the 'is completed' test with the fence's
>>> equivalent. Currently, that simply chains on to the original request
>>> implementation. A future patch will improve this.
>> But this forces everyone to do the heavyweight polling until the request
>> is completed?
> Not sure what you mean by heavy weight polling. And as described, this is only an intermediate step.

Just the lazy_coherency removal maybe?  Chris?

Jesse