linux-kernel - Re: [PATCH v2 06/11] drm: Use state helper instead of plane state pointer in atomic

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Date:   Mon, 25 Jan 2021 10:07:44 +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>, Sean Paul <sean@...rly.run>,
        freedreno@...ts.freedesktop.org, Tomi Valkeinen <tomba@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Jyri Sarha <jyri.sarha@....fi>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        linux-arm-msm@...r.kernel.org, Shawn Guo <shawnguo@...nel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 06/11] drm: Use state helper instead of plane state
 pointer in atomic_check

Hi Ville,

On Fri, Jan 22, 2021 at 02:07:22PM +0200, Ville Syrjälä wrote:
> On Thu, Jan 21, 2021 at 05:35:31PM +0100, Maxime Ripard wrote:
> > Many drivers reference the plane->state pointer in order to get the
> > current plane state in their atomic_check hook, which would be the old
> > plane state in the global atomic state since _swap_state hasn't happened
> > when atomic_check is run.
> > 
> > Use the drm_atomic_get_old_plane_state helper to get that state to make
> > it more obvious.
> > 
> > This was made using the coccinelle script below:
> > 
> > @ plane_atomic_func @
> > identifier helpers;
> > identifier func;
> > @@
> > 
> > static struct drm_plane_helper_funcs helpers = {
> > 	...,
> > 	.atomic_check = func,
> > 	...,
> > };
> > 
> > @ replaces_old_state @
> > identifier plane_atomic_func.func;
> > identifier plane, state, plane_state;
> > @@
> > 
> >  func(struct drm_plane *plane, struct drm_atomic_state *state) {
> >  	...
> > -	struct drm_plane_state *plane_state = plane->state;
> > +	struct drm_plane_state *plane_state = drm_atomic_get_old_plane_state(state, plane);
> >  	...
> >  }
> > 
> > @@
> > identifier plane_atomic_func.func;
> > identifier plane, state, plane_state;
> > @@
> > 
> >  func(struct drm_plane *plane, struct drm_atomic_state *state) {
> >  	struct drm_plane_state *plane_state = drm_atomic_get_old_plane_state(state, plane);
> >  	...
> > -	plane->state
> > +	plane_state
> >  	...
> 
> We don't need the <... ...> style here? It's been a while since
> I did any serious cocci so I'm getting a bit rusty on the details...

You're right, I've changed it and caught some more users (ingenic). I'll update it.

> Otherwise looks great
> Reviewed-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>

Thanks!
Maxime

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