linux-kernel - Re: [PATCH v2 34/35] drm/bridge: tc358768: Convert to atomic helpers

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Message-ID: <btehhpvkv6iqd4pofumspqbxzr5gxwp6vs5oh7vflbcmzqj5wz@s6yem2ryw6vs>
Date: Wed, 12 Feb 2025 02:38:52 +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 v2 34/35] drm/bridge: tc358768: Convert to atomic helpers

On Tue, Feb 11, 2025 at 03:33:58PM +0100, Maxime Ripard wrote:
> On Sun, Feb 09, 2025 at 09:13:36AM +0200, Dmitry Baryshkov wrote:
> > On Tue, Feb 04, 2025 at 03:58:02PM +0100, Maxime Ripard wrote:
> > > The tc358768 driver follows the drm_encoder->crtc pointer that is
> > > deprecated and shouldn't be used by atomic drivers.
> > > 
> > > This was due to the fact that we did't have any other alternative to
> > > retrieve the CRTC pointer. Fortunately, the crtc pointer is now provided
> > > in the bridge state, so we can move to atomic callbacks and drop that
> > > deprecated pointer usage.
> > > 
> > > Signed-off-by: Maxime Ripard <mripard@...nel.org>
> > > ---
> > >  drivers/gpu/drm/bridge/tc358768.c | 30 +++++++++++++++++++++++-------
> > >  1 file changed, 23 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c
> > > index 6db18d1e8824dd7d387211d6d1e668645cf88bbe..6ff6b29e8075d7c6fa0b74b4fec83c5230512d96 100644
> > > --- a/drivers/gpu/drm/bridge/tc358768.c
> > > +++ b/drivers/gpu/drm/bridge/tc358768.c
> > > @@ -601,17 +601,29 @@ static void tc358768_bridge_disable(struct drm_bridge *bridge)
> > >  	ret = tc358768_clear_error(priv);
> > >  	if (ret)
> > >  		dev_warn(priv->dev, "Software disable failed: %d\n", ret);
> > >  }
> > >  
> > > +static void tc358768_bridge_atomic_disable(struct drm_bridge *bridge,
> > > +					   struct drm_atomic_state *state)
> > > +{
> > > +	tc358768_bridge_disable(bridge);
> > > +}
> > > +
> > 
> > Please change corresponding functions into atomic_disable() and
> > atomic_post_disable(). Calling sites have access to the atomic state, so
> > there is no need to have yet another wrapper.
> 
> It's pretty hard to do (at least without the hardware), both
> tc358768_bridge_disable() and tc358768_bridge_post_disable() have
> multiple call sites in the driver, and passing a state enabling the
> bridge doesn't make sense for those.

I think it makes sense. The function knows that the bridge needs to be
disabled. The state is totally unused (or it can be used to get
connectors / CRTC / etc).

> 
> I guess I can still drop that patch.
> 
> Maxime



-- 
With best wishes
Dmitry