linux-kernel - Re: [PATCH v2 08/11] drm: Rename plane->state variables in atomic update and disable

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Message-ID: <20210125105218.kv63vjbxz5b35hdo@gilmour>
Date:   Mon, 25 Jan 2021 11:52:18 +0100
From:   Maxime Ripard <maxime@...no.tech>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Neil Armstrong <narmstrong@...libre.com>,
        Xinliang Liu <xinliang.liu@...aro.org>,
        Liviu Dudau <liviu.dudau@....com>,
        Philippe Cornu <philippe.cornu@...com>,
        Paul Cercueil <paul@...pouillou.net>,
        linux-tegra@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        linux-stm32@...md-mailman.stormreply.com,
        Jerome Brunet <jbrunet@...libre.com>,
        Marek Vasut <marex@...x.de>,
        Yannick Fertre <yannick.fertre@...com>,
        linux-samsung-soc@...r.kernel.org,
        Joonyoung Shim <jy0922.shim@...sung.com>,
        Kevin Hilman <khilman@...libre.com>,
        linux-mediatek@...ts.infradead.org,
        Russell King <linux@...linux.org.uk>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-rockchip@...ts.infradead.org,
        Xinwei Kong <kong.kongxinwei@...ilicon.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-arm-msm@...r.kernel.org, Dave Airlie <airlied@...hat.com>,
        linux-mips@...r.kernel.org,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Chen Feng <puck.chen@...ilicon.com>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Alison Wang <alison.wang@....com>,
        dri-devel@...ts.freedesktop.org,
        Laurentiu Palcu <laurentiu.palcu@....nxp.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-amlogic@...ts.infradead.org, freedreno@...ts.freedesktop.org,
        Sean Paul <sean@...rly.run>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        linux-arm-kernel@...ts.infradead.org,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Tomi Valkeinen <tomba@...nel.org>,
        Jyri Sarha <jyri.sarha@....fi>,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Sandy Huang <hjc@...k-chips.com>, linux-kernel@...r.kernel.org,
        Vincent Abriou <vincent.abriou@...com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Tian Tao <tiantao6@...ilicon.com>
Subject: Re: [PATCH v2 08/11] drm: Rename plane->state variables in atomic
 update and disable

Hi Ville,

On Fri, Jan 22, 2021 at 02:15:07PM +0200, Ville Syrjälä wrote:
> On Thu, Jan 21, 2021 at 05:35:33PM +0100, Maxime Ripard wrote:
> > Some drivers are storing the plane->state pointer in atomic_update and
> > atomic_disable in a variable simply called state, while the state passed
> > as an argument is called old_state.
> > 
> > In order to ease subsequent reworks and to avoid confusing or
> > inconsistent names, let's rename those variables to new_state.
> > 
> > This was done using the following coccinelle script, plus some manual
> > changes for mtk and tegra.
> > 
> > @ plane_atomic_func @
> > identifier helpers;
> > identifier func;
> > @@
> > 
> > (
> >  static const struct drm_plane_helper_funcs helpers = {
> >  	...,
> >  	.atomic_disable = func,
> > 	...,
> >  };
> > |
> >  static const struct drm_plane_helper_funcs helpers = {
> >  	...,
> >  	.atomic_update = func,
> > 	...,
> >  };
> > )
> > 
> > @ moves_new_state_old_state @
> > identifier plane_atomic_func.func;
> > identifier plane;
> > symbol old_state;
> > symbol state;
> > @@
> > 
> >  func(struct drm_plane *plane, struct drm_plane_state *old_state)
> >  {
> >  	...
> > -	struct drm_plane_state *state = plane->state;
> > +	struct drm_plane_state *new_state = plane->state;
> > 	...
> >  }
> > 
> > @ depends on moves_new_state_old_state @
> > identifier plane_atomic_func.func;
> > identifier plane;
> > identifier old_state;
> > symbol state;
> > @@
> > 
> >  func(struct drm_plane *plane, struct drm_plane_state *old_state)
> >  {
> >  	<...
> > -	state
> > +	new_state
> > 	...>
> 
> Was going to say that this migh eat something else, but I guess
> the dependency prevents that?

Yeah, the dependency takes care of this

> Another way to avoid that I suppose would be to declare 'state'
> as
> symbol moves_new_state_old_state.state;
> 
> That would probably make the intent a bit more obvious, even with
> the dependency. Or does a dependency somehow automagically imply
> that?

I'm not sure if it does, but it's a symbol here not an identifier or an
expression, so here moves_new_state_old_state.state would always resolve
to state (and only state) anyway

Maxime

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