linux-kernel - Re: [PATCH v5 04/16] drm/atomic: Introduce helper to lookup connector by encoder

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Message-ID: <20250306092102.77583816@bootlin.com>
Date: Thu, 6 Mar 2025 09:21:02 +0100
From: Herve Codina <herve.codina@...tlin.com>
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, Dmitry Baryshkov
 <dmitry.baryshkov@...aro.org>, Simona Vetter <simona.vetter@...ll.ch>
Subject: Re: [PATCH v5 04/16] drm/atomic: Introduce helper to lookup
 connector by encoder

Hi Maxime,
Hi Maxime,

On Tue, 04 Mar 2025 12:10:47 +0100
Maxime Ripard <mripard@...nel.org> wrote:

> With the bridges switching over to drm_bridge_connector, the direct
> association between a bridge driver and its connector was lost.
> 
> This is mitigated for atomic bridge drivers by the fact you can access
> the encoder, and then call drm_atomic_get_old_connector_for_encoder() or
> drm_atomic_get_new_connector_for_encoder() with drm_atomic_state.
> 
> This was also made easier by providing drm_atomic_state directly to all
> atomic hooks bridges can implement.
> 
> However, bridge drivers don't have a way to access drm_atomic_state
> outside of the modeset path, like from the hotplug interrupt path or any
> interrupt handler.
> 
> Let's introduce a function to retrieve the connector currently assigned
> to an encoder, without using drm_atomic_state, to make these drivers'
> life easier.
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Co-developed-by: Simona Vetter <simona.vetter@...ll.ch>
> Signed-off-by: Maxime Ripard <mripard@...nel.org>
> ---
>  drivers/gpu/drm/drm_atomic.c | 45 ++++++++++++++++++++++++++++++++++++++++++++
>  include/drm/drm_atomic.h     |  3 +++
>  2 files changed, 48 insertions(+)
> 

Tested the drm_atomic_get_connector_for_encoder() in the context of the
ti-sn65dsi83 driver recovery process (later modification in this series).

Tested-by: Herve Codina <herve.codina@...tlin.com>

Best regards,
Hervé