linux-kernel - Re: [PATCHv3 2/3] drm/prime: Introduce drm_gem_prime_import_platform

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Message-ID: <20170503150703.o2oenjd4gy65uwva@phenom.ffwll.local>
Date:   Wed, 3 May 2017 17:07:03 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Laura Abbott <labbott@...hat.com>
Cc:     Chris Wilson <chris@...is-wilson.co.uk>,
        Sean Paul <seanpaul@...omium.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Sumit Semwal <sumit.semwal@...aro.org>,
        intel-gfx@...ts.freedesktop.org,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
Subject: Re: [PATCHv3 2/3] drm/prime: Introduce drm_gem_prime_import_platform

On Wed, May 03, 2017 at 07:40:51AM -0700, Laura Abbott wrote:
> On 05/03/2017 12:39 AM, Daniel Vetter wrote:
> > On Tue, May 02, 2017 at 09:22:13PM +0100, Chris Wilson wrote:
> >> On Tue, May 02, 2017 at 10:02:07AM -0700, Laura Abbott wrote:
> >>>  /**
> >>> + * drm_gem_prime_import_platform - alternate implementation of the import callback
> >>> + * @dev: drm_device to import into
> >>> + * @dma_buf: dma-buf object to import
> >>> + *
> >>> + * This is identical to drm_gem_prime_import except the device used for dma_buf
> >>> + * attachment is an internal platform device instead of the standard device
> >>> + * structure. The use of this function should be limited to drivers that do not
> >>> + * set up an underlying device structure.
> >>> + */
> >>> +struct drm_gem_object *drm_gem_prime_import_platform(struct drm_device *dev,
> >>
> >> Simpler soluation will be for the caller to provide the platformdev?
> >>
> >> That works nicely for the vgem case, I think.
> > 
> > Yeah looking at this again, do we really need this patch? Couldn't we
> > instead change patch 1 to first allocate the fake platform device, then
> > pass that to drm_dev_alloc (instead of NULL like we do now)?
> > 
> 
> That was what I proposed in the first version and it was rejected.
> It's useful to have at least one driver with a NULL device for testing
> edge cases.

Oh drat :( I'd say dropping the coverage for NULL testing is ok, there's
no other driver than vgem using this. And now that we have vgem dma-buf
(or will, soonish) I'd expect that the same will hold for vkms, if it ever
happens.
-Daniel

> > That way no resurrection of drm_device.platform_dev is needed (and I'd
> > really like this zombie to stay dead on 2nd thought).
> > 
> 
> I had a hunch this would be unpopular but I figured it was worth a
> shot. I think an even cleaner solution is to allow passing of any
> struct device. I'll see about reworking this.
> 
> > Sry about this yet-another-round review :-/
> > -Daniel
> > 
> 
> Thanks for your patience.
> 
> Laura
> _______________________________________________
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> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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