[PATCH RFC 2/8] DRM: Armada: Add Armada DRM driver

Daniel Vetter daniel at ffwll.ch
Fri Jun 14 15:50:22 EDT 2013


On Fri, Jun 14, 2013 at 4:42 PM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Fri, Jun 14, 2013 at 04:23:22PM +0200, Daniel Vetter wrote:
>> On Thu, Jun 13, 2013 at 3:03 PM, Russell King - ARM Linux
>> <linux at arm.linux.org.uk> wrote:
>> > There's a bigger issue here - if it's possible for drm_crtc_helper_set_config()
>> > to be called with set->fb set but set->mode NULL, then we overwrite
>> > set->fb to NULL.  Again, that results in a lost reference.
>> >
>> > For the time being, I'm using this patch, which solves my dropped
>> > refcount problem, and marks the other possible dropped reference.
>> > Either that check needs to be removed or it needs to properly drop
>> > the refcount on the fb before 'losing' the reference to it.
>>
>> Scrap my other mail, I see now where the leaking happens. One of them
>> is interface abuse which is now fixed (and i915 has a bunch of BUG_ONs
>> to enforce them). The other one is indeed a real case that eluded me
>> when I've done the refcountification for drm_framebuffers. I'll hack
>> up some patches, since this seems to be a good excuse to port some of
>> the i915 modeset improvements back to the crtc helpers.
>
> If you're happy with the patch I supplied, that's probably the minimal fix
> which should go to stable kernels (I'm using 3.9 here) - this also counts
> as a "user visible bug".  It's something I've tripped over which causes
> exhausts memory and can prevent the X server from starting up.
>
> If you want me to package the patch up with a commit message and sign-off..

Your patch doesn't fix drm/i915 (since we don't use the crtc helpers
any more). And I don't think it's good to have the refcounting
partially in the drm core and partially in drivers. I've also thrown a
few more things on top just to port a few of the i915 cleanups to the
crtc helper. I'll submit my patches asap (need to test them a bit more
first).
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch



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