[Intel-gfx] [PATCH 1/2] drm/i915/guc: Simplify code by keeping kmap of guc_client object

[Chris Wilson]

On Wed, Feb 17, 2016 at 09:48:31AM -0800, Yu Dai wrote:
> 
> 
> On 02/17/2016 08:04 AM, Daniel Vetter wrote:
> >On Tue, Feb 16, 2016 at 08:47:07AM -0800, Yu Dai wrote:
> >>
> >>
> >> On 02/15/2016 07:23 AM, Dave Gordon wrote:
> >> >On 12/02/16 13:03, Tvrtko Ursulin wrote:
> >> >>
> >> >> On 11/02/16 23:09, yu.dai at intel.com wrote:
> >> >>> From: Alex Dai <yu.dai at intel.com>
> >> >>>
> >> >>> GuC client object is always pinned during its life cycle. We cache
> >> >>> the kmap of its first page, which includes guc_process_desc and
> >> >>> doorbell. By doing so, we can simplify the code where we read from
> >> >>> this page to get where GuC is progressing on work queue; and the
> >> >>> code where driver program doorbell to send work queue item to GuC.
> >> >
> >> >There's still one k(un)map_atomic() pair, in guc_add_workqueue_item().
> >> >Maybe we could get rid of that one too? So instead of kmapping only the
> >> >first page of the client, we could vmap() all three pages and so not
> >> >need to kmap_atomic() the WQ pages on the fly.
> >> >
> >> >There's a handy vmap_obj() function we might use, except it's currently
> >> >static ...
> >> >
> >> >
> >> Yes, there is a vmap_obj we can use but it is static. Actually two,
> >> vmap_batch() in i915_cmd_parser.c and vmap_obj() in intel_ringbuffer.c.
> >> Maybe it is a good idea to make it global, so GuC can use it too.
> >
> >There should be a vmap function somewhere in the dma-buf code too iirc.
> 
> Yes, i915_gem_dmabuf_vmap. Let me try to make a common helper function can be shared.

I have sent such a patch many times.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre