Re: [PATCH 03/19] gpu: drm: imx: ipuv3-plane: Mark 'crtc_state' as __always_unused

Lee Jones
2020-11-06T07:41:57Z

On Thu, 05 Nov 2020, Ahmad Fatoum wrote:

> Hello Lee,
>
> On 11/5/20 3:45 PM, Lee Jones wrote:
> > In the macro for_each_oldnew_crtc_in_state() 'crtc_state' is provided
> > as a container for state->crtcs[i].new_state, but is not utilised in
> > this use-case. We cannot simply delete the variable, so here we tell
> > the compiler that we're intentionally discarding the read value.
>
> for_each_oldnew_crtc_in_state already (void) casts the drm_crtc and the old
> drm_crtc_state to silence unused-but-set-variable warning. Should we maybe
> (void) cast the new crtc_state as well?

From what I saw, it only void casts the ones which aren't assigned.

> > Fixes the following W=1 kernel build warning(s):
> >
> > drivers/gpu/drm/imx/ipuv3-plane.c: In function ‘ipu_planes_assign_pre’:
> > drivers/gpu/drm/imx/ipuv3-plane.c:746:42: warning: variable ‘crtc_state’ set but not used [-Wunused-but-set-variable]
> >
> > Cc: Philipp Zabel <p.zabel@pengutronix.de>
> > Cc: David Airlie <airlied@linux.ie>
> > Cc: Daniel Vetter <daniel@ffwll.ch>
> > Cc: Shawn Guo <shawnguo@kernel.org>
> > Cc: Sascha Hauer <s.hauer@pengutronix.de>
> > Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> > Cc: Fabio Estevam <festevam@gmail.com>
> > Cc: NXP Linux Team <linux-imx@nxp.com>
> > Cc: dri-devel@lists.freedesktop.org
> > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > ---
> > drivers/gpu/drm/imx/ipuv3-plane.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/imx/ipuv3-plane.c b/drivers/gpu/drm/imx/ipuv3-plane.c
> > index 8a4235d9d9f1e..acc0a3ce4992f 100644
> > --- a/drivers/gpu/drm/imx/ipuv3-plane.c
> > +++ b/drivers/gpu/drm/imx/ipuv3-plane.c
> > @@ -743,7 +743,7 @@ bool ipu_plane_atomic_update_pending(struct drm_plane *plane)
> > int ipu_planes_assign_pre(struct drm_device *dev,
> > struct drm_atomic_state *state)
> > {
> > - struct drm_crtc_state *old_crtc_state, *crtc_state;
> > + struct drm_crtc_state *old_crtc_state, __always_unused *crtc_state;
> > struct drm_plane_state *plane_state;
> > struct ipu_plane_state *ipu_state;
> > struct ipu_plane *ipu_plane;
> >
>

--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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