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Date:   Tue, 13 Sep 2022 16:18:51 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Nathan Huckleberry <nhuck@google.com>
Cc:     Dan Carpenter <error27@gmail.com>, llvm@lists.linux.dev,
        Inki Dae <inki.dae@samsung.com>,
        Seung-Woo Kim <sw0312.kim@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/exynos: Fix return type for mixer_mode_valid and
 hdmi_mode_valid
Message-ID: <YyEP28J5O2Wlh4lS@dev-arch.thelio-3990X>
References: <20220913205449.154966-1-nhuck@google.com>
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On Tue, Sep 13, 2022 at 01:54:49PM -0700, Nathan Huckleberry wrote:
> The field mode_valid in exynos_drm_crtc_ops is expected to be of type
> enum drm_mode_status (*mode_valid)(struct exynos_drm_crtc *crtc,
>                                    const struct drm_display_mode *mode);
> 
> Likewise for mode_valid in drm_connector_helper_funcs.
> 
> The mismatched return type breaks forward edge kCFI since the underlying
> function definition does not match the function hook definition.
> 
> The return type of mixer_mode_valid and hdmi_mode_valid should be
> changed from int to enum drm_mode_status.
> 
> Reported-by: Dan Carpenter <error27@gmail.com>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1703
> Cc: llvm@lists.linux.dev
> Signed-off-by: Nathan Huckleberry <nhuck@google.com>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  drivers/gpu/drm/exynos/exynos_hdmi.c  | 4 ++--
>  drivers/gpu/drm/exynos/exynos_mixer.c | 5 +++--
>  2 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_hdmi.c b/drivers/gpu/drm/exynos/exynos_hdmi.c
> index 10b0036f8a2e..8453359c92e8 100644
> --- a/drivers/gpu/drm/exynos/exynos_hdmi.c
> +++ b/drivers/gpu/drm/exynos/exynos_hdmi.c
> @@ -922,8 +922,8 @@ static int hdmi_find_phy_conf(struct hdmi_context *hdata, u32 pixel_clock)
>  	return -EINVAL;
>  }
>  
> -static int hdmi_mode_valid(struct drm_connector *connector,
> -			struct drm_display_mode *mode)
> +static enum drm_mode_status hdmi_mode_valid(struct drm_connector *connector,
> +					    struct drm_display_mode *mode)
>  {
>  	struct hdmi_context *hdata = connector_to_hdmi(connector);
>  	int ret;
> diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c b/drivers/gpu/drm/exynos/exynos_mixer.c
> index 65260a658684..82f676e6d21b 100644
> --- a/drivers/gpu/drm/exynos/exynos_mixer.c
> +++ b/drivers/gpu/drm/exynos/exynos_mixer.c
> @@ -1045,8 +1045,9 @@ static void mixer_atomic_disable(struct exynos_drm_crtc *crtc)
>  	clear_bit(MXR_BIT_POWERED, &ctx->flags);
>  }
>  
> -static int mixer_mode_valid(struct exynos_drm_crtc *crtc,
> -		const struct drm_display_mode *mode)
> +static enum drm_mode_status
> +mixer_mode_valid(struct exynos_drm_crtc *crtc,
> +		 const struct drm_display_mode *mode)
>  {
>  	struct mixer_context *ctx = crtc->ctx;
>  	u32 w = mode->hdisplay, h = mode->vdisplay;
> -- 
> 2.37.2.789.g6183377224-goog
>