linux-kernel - Re: [PATCH v5 2/6] drm/bridge: Add a devm

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Message-ID: <87zibfqd1u.fsf@eliezer.anholt.net>
Date:   Fri, 04 Aug 2017 13:43:25 -0700
From:   Eric Anholt <eric@...olt.net>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     dri-devel@...ts.freedesktop.org,
        Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        linux-kernel@...r.kernel.org, Daniel Vetter <daniel.vetter@...l.ch>
Subject: Re: [PATCH v5 2/6] drm/bridge: Add a devm_ allocator for panel bridge.

Laurent Pinchart <laurent.pinchart@...asonboard.com> writes:

> Hi Eric,
>
> (CC'ing Daniel)
>
> Thank you for the patch.
>
> 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.

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