[PATCH v3 06/13] drm/sched: Add generic scheduler message interface

[Matthew Brost]

On Tue, Sep 12, 2023 at 10:23:02AM +0200, Boris Brezillon wrote:
> On Mon, 11 Sep 2023 19:16:08 -0700
> Matthew Brost <matthew.brost at intel.com> wrote:
> 
> > Add generic schedule message interface which sends messages to backend
> > from the drm_gpu_scheduler main submission thread. The idea is some of
> > these messages modify some state in drm_sched_entity which is also
> > modified during submission. By scheduling these messages and submission
> > in the same thread their is not race changing states in
> > drm_sched_entity.
> > 
> > This interface will be used in Xe, new Intel GPU driver, to cleanup,
> > suspend, resume, and change scheduling properties of a drm_sched_entity.
> > 
> > The interface is designed to be generic and extendable with only the
> > backend understanding the messages.
> 
> I didn't follow the previous discussions closely enough, but it seemed
> to me that the whole point of this 'ordered-wq for scheduler' approach
> was so you could interleave your driver-specific work items in the
> processing without changing the core. This messaging system looks like
> something that could/should be entirely driver-specific to me, and I'm
> not convinced this thin 'work -> generic_message_callback' layer is
> worth it. You can simply have your own xe_msg_process work, and a
> xe_msg_send helper that schedules this work. Assuming other drivers
> need this messaging API, they'll probably have their own message ids
> and payloads, and the automation done here is simple enough that it can
> be duplicated. That's just my personal opinion, of course, and if
> others see this message interface as valuable, I fine with it.

Good point. I am fine deleting this from the scheduler and making this
driver specific.

Matt