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

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Date:   Wed, 3 May 2017 07:40:51 -0700
From:   Laura Abbott <labbott@...hat.com>
To:     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 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.

> 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