Re: [PATCH v4 1/2] drm: bridge: Add sii902x driver

From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Mark Rutland <mark.rutland@arm.com>, Meng Yi <meng.yi@nxp.com>,
	Xiubo Li <lixiubo@cmss.chinamobile.com>,
	Pawel Moll <pawel.moll@arm.com>,
	Ian Campbell <ijc+devicetree@hellion.org.uk>,
	Alison Wang <alison.wang@nxp.com>,
	Nicolas Ferre <nicolas.ferre@atmel.com>,
	dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
	Rob Herring <robh+dt@kernel.org>,
	Alexandre Belloni <alexandre.belloni@free-electrons.com>,
	Kumar Gala <galak@codeaurora.org>,
	Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>,
	Jianwei Wang <jianwei.wang.chn@gmail.com>
Subject: Re: [PATCH v4 1/2] drm: bridge: Add sii902x driver
Date: Thu, 2 Jun 2016 10:04:15 +0200	[thread overview]
Message-ID: <20160602100415.32b26822@bbrezillon> (raw)
In-Reply-To: <20160601215602.GA7231@phenom.ffwll.local>

On Wed, 1 Jun 2016 23:56:02 +0200
Daniel Vetter <daniel@ffwll.ch> wrote:

> On Wed, Jun 01, 2016 at 06:03:37PM +0200, Boris Brezillon wrote:
> > On Tue, 17 May 2016 08:47:11 +0200
> > Daniel Vetter <daniel@ffwll.ch> wrote:
> >   
> > > > +static struct drm_encoder *sii902x_best_encoder(struct drm_connector *connector)
> > > > +{
> > > > +	struct sii902x *sii902x = connector_to_sii902x(connector);
> > > > +
> > > > +	return sii902x->bridge.encoder;
> > > > +}    
> > > 
> > > drm_atomic_helper_best_encoder should do exactly this for you. If you feel
> > > board pimp the atomic helpers to call that one by default to even remove
> > > the vfunc assingment line ;-)  
> > 
> > Just to be sure, is that what you had in mind?  
> 
> Exactly, I'll pick this one up for drm-misc. btw if you're even more
> motivated, you can go through all drivers with a static mapping from
> connector to encoder, and nuke those functions. Since if it's just a
> static mapping, the only way to do it is like the helper does.
> 
> Thanks, Daniel
> >   
> > --->8---  
> > From d218b7ea16ca35452b3174c83a207ecd406e5c88 Mon Sep 17 00:00:00 2001
> > From: Boris Brezillon <boris.brezillon@free-electrons.com>
> > Date: Wed, 1 Jun 2016 17:57:18 +0200
> > Subject: [PATCH] drm: atomic: Handle funcs->best_encoder == NULL case
> > 
> > Fallback drm_atomic_helper_best_encoder() is funcs->best_encoder() is NULL
> > so that DRM drivers can leave this hook unassigned if they know they want
> > to use drm_atomic_helper_best_encoder().

Please don't apply the patch, it's buggy.

> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> > ---
> >  drivers/gpu/drm/drm_atomic_helper.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index ddfa0d1..f6a3350 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -110,8 +110,10 @@ static int handle_conflicting_encoders(struct drm_atomic_state *state,
> >  
> >  		if (funcs->atomic_best_encoder)
> >  			new_encoder = funcs->atomic_best_encoder(connector, conn_state);
> > -		else
> > +		else if (funcs->best_encoder)
> >  			new_encoder = funcs->best_encoder(connector);
> > +		else
> > +			new_encoder = drm_atomic_helper_best_encoder(connector);
> >  
> >  		if (new_encoder) {
> >  			if (encoder_mask & (1 << drm_encoder_index(new_encoder))) {
> > 
> > 
> >   
> 

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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