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From: Daniel Stone <daniel@fooishbar.org>
Date: Fri, 16 Feb 2024 14:02:10 +0000
Message-ID: <CAPj87rNi4=0Os3dNANmWbHm=sCeyogYDG0ZJUED2PGn0U-7tEg@mail.gmail.com>
Subject: Re: [PATCH 1/2] drm/tidss: Fix initial plane zpos values
To: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Cc: Marius Vlad <marius.vlad@collabora.com>, 
	Pekka Paalanen <pekka.paalanen@haloniitty.fi>, Jyri Sarha <jyri.sarha@iki.fi>, 
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, 
	Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, 
	Sam Ravnborg <sam@ravnborg.org>, Devarsh Thakkar <devarsht@ti.com>, Aradhya Bhatia <a-bhatia1@ti.com>, 
	Francesco Dolcini <francesco@dolcini.it>, Tomi Valkeinen <tomi.valkeinen@ti.com>, 
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, 
	"wayland-devel@lists.freedesktop.org" <wayland-devel@lists.freedesktop.org>, Randolph Sapp <rs@ti.com>
Content-Type: text/plain; charset="UTF-8"

Hi,

On Fri, 16 Feb 2024 at 09:00, Tomi Valkeinen
<tomi.valkeinen@ideasonboard.com> wrote:
> On 13/02/2024 13:39, Daniel Stone wrote:
> > Specifically, you probably want commits 4cde507be6a1 and 58dde0e0c000.
> > I think the window of breakage was small enough that - assuming either
> > those commits or an upgrade to Weston 12/13 fixes it - we can just ask
> > people to upgrade to a fixed Weston.
> >
> >>> Presuming this is not related to any TI specific code, I guess it's a
> >>> regression in the sense that at some point Weston added the support to use
> >>> planes for composition, so previously with only a single plane per display
> >>> there was no issue.
> >
> > That point was 12 years ago, so not that novel. ;)
>
> Hmm, so do I understand it right, the plane code from 12 years back
> supposedly works ok, but somewhere around Weston 10 something broke, but
> was fixed with the commits you mention above?

We always had plane support but pre-zpos; we added support for zpos a
couple/few releases ago, but then massively refactored it ... so it
could've always been broken, or could've been broken for as long as we
have zpos, or it could've just been a small window in between the
refactor.