From: Andrzej Hajda <a.hajda@samsung.com>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm/exynos/dsi: simplify hotplug code
Date: Thu, 06 Nov 2014 14:30:26 +0100 [thread overview]
Message-ID: <545B77F2.5060203@samsung.com> (raw)
In-Reply-To: <20141106131824.GC12260@ulmo>
On 11/06/2014 02:18 PM, Thierry Reding wrote:
> On Thu, Nov 06, 2014 at 12:35:48PM +0100, Andrzej Hajda wrote:
>> Exynos DSI driver uses DSI bus attach/detach callbacks to implement
>> panel hotplug mechanism. The patch moves panel attachment code
>> from .detect callback to DSI bus callbacks. It makes the code
>> simpler and more straightforward.
>> The patch removes also redundant and lock unprotected dpms_off call
>> from unbind code.
>>
>> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
>> ---
>> Hi,
>>
>> This patch simplifies drm part of hotplug mechanism in dsi attach/detach callbacks.
>> It also fixes minor bug with unprotected dpms_off call, which is unneccesary anyway.
>>
>> But the main reason I have looked at this code again is to show that
>> we do not need zombie panels, we can kill panels properly if we have hot plug/unplug
>> callbacks. And it is quite simple: we just need to take mode_config.mutex locks
>> to synchronize dsi callbacks with drm, nothing more.
>> It works nicely because of two things:
>> - panel callbacks are called always under this lock,
>> - callbacks are installed after drmdev creation and deinstalled before drmdev destroy -
>> this way we assure drmdev is always present in callbacks.
> Again, something like what you propose is going to work only for DSI
> devices. What we need is a solution that works for all other types of
> panels, too. This is even more important when we consider bridges
> because they are less likely to be on a DSI bus.
Again:) I say that all we need are just hot plug/unplug callbacks,
no zombie panels, no revoke, no try_module_get, etc.
Regards
Andrzej
>
> Thierry
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prev parent reply other threads:[~2014-11-06 13:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-06 11:35 [PATCH] drm/exynos/dsi: simplify hotplug code Andrzej Hajda
2014-11-06 13:18 ` Thierry Reding
2014-11-06 13:30 ` Andrzej Hajda [this message]
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