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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Tue, 1 Jun 2021 22:07:38 -0400
Message-ID: <CADnq5_Na=AdNCoQpDPVJ=5078s8C7SNMBo295H-Jp1fQZWkmCw@mail.gmail.com>
Subject: Re: [PATCH] drm/amd/display: fix gcc set but not used warning of
 variable 'old_plane_state'
To:     Yu Kuai <yukuai3@huawei.com>
Cc:     "Wentland, Harry" <harry.wentland@amd.com>,
        "Leo (Sunpeng) Li" <sunpeng.li@amd.com>,
        "Deucher, Alexander" <alexander.deucher@amd.com>,
        Christian Koenig <christian.koenig@amd.com>,
        xinhui pan <Xinhui.Pan@amd.com>,
        Dave Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>, yi.zhang@huawei.com,
        Maling list - DRI developers 
        <dri-devel@lists.freedesktop.org>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>
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Applied.  Thanks!

Alex

On Sat, May 29, 2021 at 5:19 AM Yu Kuai <yukuai3@huawei.com> wrote:
>
> define a new macro for_each_new_plane_in_state_reverse to replace
> for_each_oldnew_plane_in_state_reverse, so that the unused variable
> 'old_plane_state' can be removed.
>
> Fix gcc warning:
> drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:10066:26: war=
ning:
>  variable =E2=80=98old_plane_state=E2=80=99 set but not used [-Wunused-bu=
t-set-variable]
>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  4 ++--
>  include/drm/drm_atomic.h                          | 12 ++++++++++++
>  2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/=
gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index f7a5e5b48ea6..9f4b334bc071 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -10063,11 +10063,11 @@ static int validate_overlay(struct drm_atomic_s=
tate *state)
>  {
>         int i;
>         struct drm_plane *plane;
> -       struct drm_plane_state *old_plane_state, *new_plane_state;
> +       struct drm_plane_state *new_plane_state;
>         struct drm_plane_state *primary_state, *cursor_state, *overlay_st=
ate =3D NULL;
>
>         /* Check if primary plane is contained inside overlay */
> -       for_each_oldnew_plane_in_state_reverse(state, plane, old_plane_st=
ate, new_plane_state, i) {
> +       for_each_new_plane_in_state_reverse(state, plane, new_plane_state=
, i) {
>                 if (plane->type =3D=3D DRM_PLANE_TYPE_OVERLAY) {
>                         if (drm_atomic_plane_disabling(plane->state, new_=
plane_state))
>                                 return 0;
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index ac5a28eff2c8..8f1350e599eb 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -895,6 +895,18 @@ void drm_state_dump(struct drm_device *dev, struct d=
rm_printer *p);
>                               (old_plane_state) =3D (__state)->planes[__i=
].old_state,\
>                               (new_plane_state) =3D (__state)->planes[__i=
].new_state, 1))
>
> +/**
> + * for_each_new_plane_in_state_reverse - other than only tracking new st=
ate,
> + * it's the same as for_each_oldnew_plane_in_state_reverse
> + */
> +#define for_each_new_plane_in_state_reverse(__state, plane, new_plane_st=
ate, __i) \
> +       for ((__i) =3D ((__state)->dev->mode_config.num_total_plane - 1);=
 \
> +            (__i) >=3D 0;                                               =
 \
> +            (__i)--)                                                   \
> +               for_each_if ((__state)->planes[__i].ptr &&              \
> +                            ((plane) =3D (__state)->planes[__i].ptr,    =
 \
> +                             (new_plane_state) =3D (__state)->planes[__i=
].new_state, 1))
> +
>  /**
>   * for_each_old_plane_in_state - iterate over all planes in an atomic up=
date
>   * @__state: &struct drm_atomic_state pointer
> --
> 2.25.4
>