linux-kernel - Re: [PATCH v2 1/2] drm/bridge-connector: reset the HDMI connector state

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Date: Tue, 25 Jun 2024 19:38:22 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Maxime Ripard <mripard@...nel.org>
Cc: 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>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Daniel Vetter <daniel@...ll.ch>, Dave Stevenson <dave.stevenson@...pberrypi.com>, 
	Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>, 
	dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] drm/bridge-connector: reset the HDMI connector
 state

On Tue, Jun 25, 2024 at 05:49:54PM GMT, Maxime Ripard wrote:
> On Tue, Jun 25, 2024 at 06:05:33PM GMT, Dmitry Baryshkov wrote:
> > On Tue, 25 Jun 2024 at 18:02, Maxime Ripard <mripard@...nel.org> wrote:
> > >
> > > Hi,
> > >
> > > On Sun, Jun 23, 2024 at 08:40:12AM GMT, Dmitry Baryshkov wrote:
> > > > On HDMI connectors which use drm_bridge_connector and DRM_BRIDGE_OP_HDMI
> > > > IGT chokes on the max_bpc property in several kms_properties tests due
> > > > to the the drm_bridge_connector failing to reset HDMI-related
> > > > properties.
> > > >
> > > > Call __drm_atomic_helper_connector_hdmi_reset() if there is a
> > > > the drm_bridge_connector has bridge_hdmi.
> > > >
> > > > Note, the __drm_atomic_helper_connector_hdmi_reset() is moved to
> > > > drm_atomic_state_helper.c because drm_bridge_connector.c can not depend
> > > > on DRM_DISPLAY_HDMI_STATE_HELPER. At the same time it is impossible to
> > > > call this function from HDMI bridges, there is is no function that
> > > > corresponds to the drm_connector_funcs::reset().
> > >
> > > Why can't it depend on DRM_DISPLAY_HDMI_STATE_HELPER?
> > 
> > Is it okay to have DRM_KMS_HELPER to depend unconditionally or select
> > DRM_DISPLAY_HDMI_STATE_HELPER?
> 
> No, but it's not clear to me why drm_bridge_connector is part of
> DRM_KMS_HELPER? It doesn't seem to be called from the core but only
> drivers, just like DRM_PANEL_BRIDGE which has a separate config option

But then DRM_PANEL_BRIDGE is also linked into drm_kms_helper.ko. I can't
really say that I understand the definition of various helper modules,
but my taste tells me that code from drm/*.c should not depend directly
on the code from drm/display/*.c.

-- 
With best wishes
Dmitry