[Intel-gfx] [PATCH v5 4/5] drm: Add library for shmem backed GEM objects

Eric Anholt eric at anholt.net
Wed Nov 28 21:52:56 UTC 2018


Daniel Vetter <daniel at ffwll.ch> writes:

> On Tue, Nov 27, 2018 at 12:38:44PM -0800, Eric Anholt wrote:
>> Daniel Vetter <daniel at ffwll.ch> writes:
>> 
>> > On Mon, Nov 26, 2018 at 04:36:21PM -0800, Eric Anholt wrote:
>> >> Noralf Trønnes <noralf at tronnes.org> writes:
>> >> > +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
>> >> > +{
>> >> > +	struct drm_gem_object *obj = vma->vm_private_data;
>> >> > +	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>> >> > +
>> >> > +	drm_gem_shmem_put_pages(shmem);
>> >> > +	drm_gem_vm_close(vma);
>> >> > +}
>> >> > +
>> >> > +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
>> >> > +	.fault = drm_gem_shmem_fault,
>> >> > +	.open = drm_gem_vm_open,
>> >> > +	.close = drm_gem_shmem_vm_close,
>> >> > +};
>> >> > +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
>> >> 
>> >> I just saw a warning from drm_gem_shmem_put_pages() for
>> >> !shmem->pages_use_count -- I think drm_gem_vm_open() needs to
>> >> drm_gem_shmem_get_pages().
>> >
>> > Yeah we need a drm_gem_shmem_vm_open here.
>> 
>> Adding one of those fixed my refcounting issues, so I've sent out a v6
>> with it.
>
> Just realized that I've reviewed this patch already, spotted that vma
> management issue there too. Plus a pile of other things. From reading that
> other thread discussion with Noralf concluded with "not yet ready for
> prime time" unfortunately :-/

I saw stuff about how it wasn't usable for SPI because SPI does weird
things with DMA mapping.  Was there something else?
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