Re: [PATCH v5 2/6] drm/bridge: Add a devm_ allocator for panel bridge.

From: Laurent Pinchart
Date: Fri Aug 04 2017 - 17:25:02 EST

Hi Eric,

On Friday 04 Aug 2017 13:43:25 Eric Anholt wrote:
> Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> writes:
> > On Tuesday 18 Jul 2017 14:05:06 Eric Anholt wrote:
> >> This will let drivers reduce the error cleanup they need, in
> >> particular the "is_panel_bridge" flag.
> >>
> >> v2: Slight cleanup of remove function by Andrzej
> >
> > I just want to point out that, in the context of Daniel's work on
> > hot-unplug, 90% of the devm_* allocations are wrong and will get in the
> > way. All DRM core objects that are accessible one way or another from
> > userspace will need to be properly reference-counted and freed only when
> > the last reference disappears, which could be well after the
> > corresponding device is removed. I believe this could be one such objects
> > :-/
> Sure, if you're hotplugging, your life is pain. For non-hotpluggable
> devices, like our SOC platform devices (current panel-bridge consumers),
> this still seems like an excellent simplification of memory management.

It encourages driver writers to write code that they will have to fix later.
That's certainly a simplification, but certainly not a good thing in my
opinion :-)


Laurent Pinchart