linux-kernel - Re: [PATCH v3 31/37] drm/bridge: Provide pointers to the connector and crtc in bridge state

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Message-ID: <h6nqaxoq5eohevpdlym4g24lqeeqhapzmbjdi2lyyjrhyu7wrj@omypjnlxniz2>
Date: Fri, 14 Feb 2025 15:28:04 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Maxime Ripard <mripard@...nel.org>
Cc: 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 31/37] drm/bridge: Provide pointers to the connector
 and crtc in bridge state

On Fri, Feb 14, 2025 at 02:06:34PM +0100, Maxime Ripard wrote:
> On Thu, Feb 13, 2025 at 06:32:39PM +0200, Dmitry Baryshkov wrote:
> > On Thu, Feb 13, 2025 at 03:43:50PM +0100, Maxime Ripard wrote:
> > > Now that connectors are no longer necessarily created by the bridges
> > > drivers themselves but might be created by drm_bridge_connector, it's
> > > pretty hard for bridge drivers to retrieve pointers to the connector and
> > > CRTC they are attached to.
> > > 
> > > Indeed, the only way to retrieve the CRTC is to follow the drm_bridge
> > > encoder field, and then the drm_encoder crtc field, both of them being
> > > deprecated.
> > > 
> > > And for the connector, since we can have multiple connectors attached to
> > > a CRTC, we don't really have a reliable way to get it.
> > 
> > The same comment as for v2:
> > 
> > It's not very precise:
> > 
> >  connector = drm_atomic_get_new_connector_for_encoder(state, bridge->encoder);
> > 
> > Is that unreliable somehow?
> 
> Then I'm not sure what you want here (and in v2) either. Do you want me
> to drop this patch because it's redundant, drop it, something else?

No, basically to expand the commit message. It states that there was no
reliable way to get the connector, but there was one. I'd mention that
getting CRTC and connector via the state results in a boilerplate code
and complicates bridge drivers.

-- 
With best wishes
Dmitry