Re: [Intel-gfx] [PATCH 1/8] drm/omap: Simplify the rotation-on-crtc hack

From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@intel.com>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [Intel-gfx] [PATCH 1/8] drm/omap: Simplify the rotation-on-crtc hack
Date: Mon, 31 Jul 2017 14:56:16 +0300	[thread overview]
Message-ID: <6b34707b-fed4-1c1d-e050-9eebee2a923d@ti.com> (raw)
In-Reply-To: <5875908.nkarGct6Ju@avalon>

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On 31/07/17 14:48, Laurent Pinchart wrote:

>>> The comment about read lock is only valid when the plane is bound to the
>>> crtc. In general this is not always the case. You can only peak at
>>> plane->state when crtc->state->plane_mask & BIT(drm_plane_index(plane))
>>> is true.
>>>
>>> I think we might need -EDEADLK handling for getprop then, even though it's
>>> not optimal. :(
>>
>> Well both the old an new way only worked because we grab all the locks
>> unconditionally. And I'd really want to avoid get_prop being anything
>> but a simple lookup. Unfortuantely that breaks omapdrm, so no idea
>> what exactly to do here.
>>
>> In a way adding properties without standardizing them across drivers
>> first was a really bad idea, because then we have disjoint sets of
>> uapi expectations, and there's just no way to make that work.
>>
>> I guess one radical approach might be to make this the "standard", and
>> just redirect rotation from the CRTC to the primary plane.
>>
>> Or omapdrm needs to duplicate the property properly, and update one if
>> the other is set. I think that's probably the most workable approach.
> 
> Maybe the first question we should answer is whether this hack is still needed 
> in the omapdrm driver. Tomi, do you know whether userspace still needs this ?

The omap X driver uses legacy modesetting and the rotation property for
the crtc.

 Tomi

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