From: "Noralf Trønnes" <noralf@tronnes.org>
To: Ilia Mirkin <imirkin@alum.mit.edu>, Eric Anholt <eric@anholt.net>
Cc: Daniel Vetter <daniel.vetter@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
Thierry Reding <thierry.reding@gmail.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH v5 2/6] drm/bridge: Add a devm_ allocator for panel bridge.
Date: Sat, 5 Aug 2017 12:59:07 +0200 [thread overview]
Message-ID: <fb6b614b-15fb-ff4d-0ffd-fbf481efa8ca@tronnes.org> (raw)
In-Reply-To: <CAKb7UvgARVWX9=_mGAPZTh6SWQ_PhTZVzOoA-rruajWPsdJujA@mail.gmail.com>
(I had to switch to Daniel's Intel address to get this sent)
Den 05.08.2017 00.19, skrev Ilia Mirkin:
> 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.
If drm_open() gets a ref on dev->dev and puts it in drm_release(),
won't that delay devm_* cleanup until userspace is done?
next prev parent reply other threads:[~2017-08-05 10:59 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
2017-08-05 10:59 ` Noralf Trønnes [this message]
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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