From: Ilia Mirkin <imirkin@alum.mit.edu>
To: Eric Anholt <eric@anholt.net>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
Archit Taneja <architt@codeaurora.org>,
Andrzej Hajda <a.hajda@samsung.com>,
Thierry Reding <thierry.reding@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Daniel Vetter <daniel.vetter@ffwl.ch>
Subject: Re: [PATCH v5 2/6] drm/bridge: Add a devm_ allocator for panel bridge.
Date: Fri, 4 Aug 2017 18:19:55 -0400 [thread overview]
Message-ID: <CAKb7UvgARVWX9=_mGAPZTh6SWQ_PhTZVzOoA-rruajWPsdJujA@mail.gmail.com> (raw)
In-Reply-To: <87zibfqd1u.fsf@eliezer.anholt.net>
On Fri, Aug 4, 2017 at 4:43 PM, Eric Anholt <eric@anholt.net> wrote:
> Laurent Pinchart <laurent.pinchart@ideasonboard.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.
At that point you may as well make your module non-unloadable, and
return failure when trying to remove a device from management by the
driver (whatever the opposite of "probe" is, I forget). Hotplugging
doesn't only happen when physically removing, it can happen for all
kinds of reasons... and userspace may still hold references in some of
those cases.
next prev parent reply other threads:[~2017-08-04 22:19 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-18 21:05 [PATCH v5 1/6] drm/vc4: Avoid using vrefresh==0 mode in DSI htotal math Eric Anholt
2017-07-18 21:05 ` [PATCH v5 2/6] drm/bridge: Add a devm_ allocator for panel bridge Eric Anholt
2017-07-19 8:58 ` Philippe CORNU
2017-07-26 22:43 ` Eric Anholt
2017-08-04 13:46 ` Laurent Pinchart
2017-08-04 14:57 ` Laurent Pinchart
2017-08-04 20:43 ` Eric Anholt
2017-08-04 21:25 ` Laurent Pinchart
2017-08-04 22:19 ` Ilia Mirkin [this message]
2017-08-05 10:59 ` Noralf Trønnes
2017-08-05 14:47 ` Noralf Trønnes
2017-08-07 9:25 ` Daniel Vetter
2017-08-07 10:22 ` Laurent Pinchart
2017-08-07 14:37 ` Noralf Trønnes
2017-08-07 14:59 ` Daniel Vetter
2017-08-07 21:54 ` Laurent Pinchart
2017-07-18 21:05 ` [PATCH v5 3/6] drm/vc4: Delay DSI host registration until the panel has probed Eric Anholt
2017-08-04 9:04 ` Boris Brezillon
2017-07-18 21:05 ` [PATCH v5 4/6] drm: Allow DSI devices to be registered before the host registers Eric Anholt
2017-07-19 20:31 ` Eric Anholt
2017-07-18 21:05 ` [PATCH v5 5/6] dt-bindings: Document the Raspberry Pi Touchscreen nodes Eric Anholt
2017-07-18 21:05 ` [PATCH v5 6/6] drm/panel: Add support for the Raspberry Pi 7" Touchscreen Eric Anholt
2017-08-04 8:53 ` [PATCH v5 1/6] drm/vc4: Avoid using vrefresh==0 mode in DSI htotal math Boris Brezillon
2017-08-04 21:15 ` Eric Anholt
2017-08-09 14:42 ` Boris Brezillon
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