linux-kernel - Re: [PATCH v3 1/7] drm/connector: hdmi: accept NULL for Audio Infoframe

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Date: Thu, 30 May 2024 14:20:33 +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>, Rob Clark <robdclark@...il.com>, 
	Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org, 
	freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/7] drm/connector: hdmi: accept NULL for Audio
 Infoframe

On Thu, May 30, 2024 at 10:49:26AM +0200, Maxime Ripard wrote:
> Hi,
> 
> On Thu, May 30, 2024 at 02:12:24AM GMT, Dmitry Baryshkov wrote:
> > Allow passing NULL as audio infoframe as a way to disable Audio
> > Infoframe generation.
> > 
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > ---
> >  drivers/gpu/drm/display/drm_hdmi_state_helper.c | 14 ++++++++++----
> >  1 file changed, 10 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> > index ce96837eea65..5356723d21f5 100644
> > --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> > +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> > @@ -681,7 +681,7 @@ EXPORT_SYMBOL(drm_atomic_helper_connector_hdmi_update_infoframes);
> >  /**
> >   * drm_atomic_helper_connector_hdmi_update_audio_infoframe - Update the Audio Infoframe
> >   * @connector: A pointer to the HDMI connector
> > - * @frame: A pointer to the audio infoframe to write
> > + * @frame: A pointer to the audio infoframe to write or NULL to disable sending the frame
> >   *
> >   * This function is meant for HDMI connector drivers to update their
> >   * audio infoframe. It will typically be used in one of the ALSA hooks
> > @@ -704,10 +704,16 @@ drm_atomic_helper_connector_hdmi_update_audio_infoframe(struct drm_connector *co
> >  
> >  	mutex_lock(&connector->hdmi.infoframes.lock);
> >  
> > -	memcpy(&infoframe->data, frame, sizeof(infoframe->data));
> > -	infoframe->set = true;
> > +	if (frame) {
> > +		memcpy(&infoframe->data, frame, sizeof(infoframe->data));
> > +		infoframe->set = true;
> > +
> > +		ret = write_infoframe(connector, infoframe);
> > +	} else {
> > +		infoframe->set = false;
> >  
> > -	ret = write_infoframe(connector, infoframe);
> > +		ret = clear_infoframe(connector, infoframe);
> > +	}
> 
> I'm not entirely sure your commit matches your commit log? It looks like
> you follow the same pattern than the other infoframes and call
> write_infoframe if there's one, or clear_infoframe if there isn't.
> 
> So we're never passing NULL to disable? clear_infoframe is called.

This function is being called from the driver, so I want to be able to
call drm_atomic_helper_connector_hdmi_update_audio_infoframe(connector,
NULL) in order to disable sending of the Audio InfoFrame.

-- 
With best wishes
Dmitry