From: Maarten Lankhorst <email@example.com>
To: Boris Brezillon <firstname.lastname@example.org>,
Daniel Vetter <email@example.com>
Cc: firstname.lastname@example.org, email@example.com
Subject: Re: [Intel-gfx] [PATCH] drm/atomic: Acquire connection_mutex lock in drm_helper_probe_single_connector_modes.
Date: Wed, 29 Mar 2017 15:51:08 +0200 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
Op 29-03-17 om 15:31 schreef Boris Brezillon:
> On Wed, 29 Mar 2017 15:26:45 +0200
> Daniel Vetter <email@example.com> wrote:
>> On Wed, Mar 29, 2017 at 12:16:50PM +0200, Maarten Lankhorst wrote:
>>> mode_valid() and get_modes() called
>>> from drm_helper_probe_single_connector_modes()
>>> may need to look at connector->state because what a valid mode is may
>>> depend on connector properties being set. For example some HDMI modes
>>> might be rejected when a connector property forces the connector
>>> into DVI mode.
>>> Some implementations of detect() already lock all state,
>>> so we have to pass an acquire_ctx to them to prevent a deadlock.
>>> This means changing the function signature of detect() slightly,
>>> and passing the acquire_ctx for locking multiple crtc's.
>>> It might be NULL, in which case expensive operations should be avoided.
>>> intel_dp.c however ignores the force flag, so still lock
>>> connection_mutex there if needed.
>>> Signed-off-by: Maarten Lankhorst <firstname.lastname@example.org>
>>> Cc: Boris Brezillon <email@example.com>
>>> Cc: Manasi Navare <firstname.lastname@example.org>
>> Hm only noticed this now, but mixing up force with the acquire_ctx sounds
>> like very bad interface design. Yes, the only user of the new hook works
>> like that, but that's really accidental I think. I think just having the
>> ctx everywhere (for atomic drivers at least) would be a lot safer. This is
>> extremely surprising (and undocumented suprise at that).
> Yes, I was about to say the same thing: the interface is not very
> clear, and I don't understand why ctx = NULL implies force = false.
They're the same thing I fear. I could perhaps call it force_ctx instead,
but non-zero ctx implies force, and other way around. Though I guess we could
relax it, and have force = true imply ctx, but not the other way around.
Would that be ok?
dri-devel mailing list
next prev parent reply other threads:[~2017-03-29 13:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-29 10:16 [PATCH] drm/atomic: Acquire connection_mutex lock in drm_helper_probe_single_connector_modes Maarten Lankhorst
2017-03-29 10:54 ` ✓ Fi.CI.BAT: success for " Patchwork
2017-03-29 13:26 ` [PATCH] " Daniel Vetter
2017-03-29 13:31 ` [Intel-gfx] " Boris Brezillon
2017-03-29 13:51 ` Maarten Lankhorst [this message]
2017-03-29 14:06 ` Daniel Vetter
2017-03-29 14:16 ` Maarten Lankhorst
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