linux-kernel - Re: [PATCH v3 32/37] drm/bridge: Make encoder pointer deprecated

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <dksptjtgipcuuivp3tud5lhghoiqrak5t33m5pz4jtssegz75t@fanvtjdmy2pp>
Date: Mon, 17 Feb 2025 21:47:51 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Maxime Ripard <mripard@...nel.org>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Robert Foss <rfoss@...nel.org>, Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
	Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	Douglas Anderson <dianders@...omium.org>, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 32/37] drm/bridge: Make encoder pointer deprecated

On Mon, Feb 17, 2025 at 05:38:08PM +0100, Simona Vetter wrote:
> On Fri, Feb 14, 2025 at 03:29:12PM +0200, Dmitry Baryshkov wrote:
> > On Fri, Feb 14, 2025 at 02:07:18PM +0100, Maxime Ripard wrote:
> > > On Thu, Feb 13, 2025 at 06:35:15PM +0200, Dmitry Baryshkov wrote:
> > > > On Thu, Feb 13, 2025 at 03:43:51PM +0100, Maxime Ripard wrote:
> > > > > Other entities (drm_connector.crtc, drm_encoder.crtc, etc.) have
> > > > > pointer to other currently bound entities. They are all considered
> > > > > relevant only for non-atomic drivers, and generally perceived as
> > > > > deprecated in favour of the equivalent pointers in the atomic states.
> > > > 
> > > > I think there is a significant difference between mentioned fields and
> > > > drm_bridge.encoder: the former fields are variable and can change. The
> > > > latter one is static and set at the bridge attachment time. Nevertheless
> > > > I think it is a good idea to deprecate it.
> > > 
> > > I'm sorry, it's not clear to me here what you want here either. Do you
> > > want me to change anything to that patch?
> > 
> > Well... I was thinking if we should expand the commit message. Most
> > likely it's fine though. In the end, I've r-b'ed the patch.
> 
> I think this one is wrong, since the bridge->encoder link is static. This
> is unlike the connector->encoder->crtc chain, which isn't, and where you
> really want to go through the atomic states or you get funny stuff.
> 
> I don't think we have bridge chains with multiple connectors though, so
> this is fairly academic and so maybe still a good idea to make this all
> more flexible? Unless I've missed the memo and atomic bridges have
> flexible routing, and in that case yes this shouldn't be used.

No, bridges are still attached to a single encoder, however I see
Maxime's idea in uniformity. It's easier to remember that all direct
pointers are deprecated rather than remembering that bridge->encoder is
static, but everything else is dynamic and should be accessed through
the state.

> 
> Mildly confused ...
> -Sima
> -- 
> Simona Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
With best wishes
Dmitry