Re: [PATCH] drm/vkms: provide a parent device to drm_dev_init()

From: Emil Velikov <emil.l.velikov@gmail.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: "Sharma, Deepak" <deepak.sharma@amd.com>,
	Haneen Mohammed <hamohammed.sa@gmail.com>,
	Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	ML dri-devel <dri-devel@lists.freedesktop.org>,
	Sean Paul <sean@poorly.run>
Subject: Re: [PATCH] drm/vkms: provide a parent device to drm_dev_init()
Date: Mon, 29 Oct 2018 11:24:18 +0000	[thread overview]
Message-ID: <CACvgo53_fHOZN0rPH3UxN1rmER-Rg_KS8vmawQUwT+8DZs+jQg@mail.gmail.com> (raw)
In-Reply-To: <20181026102658.GI21967@phenom.ffwll.local>

On Fri, 26 Oct 2018 at 11:27, Daniel Vetter <daniel@ffwll.ch> wrote:
>
> On Fri, Oct 26, 2018 at 11:05:50AM +0100, Emil Velikov wrote:
> > From: Emil Velikov <emil.velikov@collabora.com>
> >
> > Earlier commit updated the vgem driver to improve the topology, by
> > passing a platform device as parent to drm_dev_init(). Shortly
> > afterwords we updated the core function to BUG() in order to catch any
> > buggy drivers passing NULL as parent.
> >
> > While I missed the vkms driver (as the patch predates vkms by a few
> > months), the BUG caught the issue within couple of hours.
> >
> > Swap the drm_dev_init <> platform_device_register_simple order, to
> > the driver back to life.
> >
> > Fixes: f08877e79485 ("drm: BUG_ON if passing NULL parent to drm_dev_init")
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Deepak Sharma <deepak.sharma@amd.com>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Maxime Ripard <maxime.ripard@bootlin.com>
> > Cc: Sean Paul <sean@poorly.run>
> > Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
> > Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
> > Reported-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
> > ---
> > Rodrigo, Haneen, my plan is to push the patch to the drm-misc tree. An
> > Ack/Rb will be appreciated.
>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>
Thanks, pushed via dim. Since this way breaking the 0day buildbot,
I've decided to not wait too long.

> btw just read through this stuff again, and noticed how vgem is using
> drm_gem_prime_import_dev(). I think now that your patches have landed we
> could get rid of that?

AFAICT the exynos is also using drm_gem_prime_import_dev. Having a
slightly closer look, it uses a distinct component driver for DMA.
One that varies across HW generation.

It should be doable to rework/remove that, since my knowledge in
exynos is limited, I'd refrain for now.

Thanks
-Emil
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