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From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Date: Tue, 27 Feb 2024 12:38:26 +0100
Message-ID: <CAPybu_2JoNfr158FXqYGUV=JuTW8i85XM6cf7K40_xZe9m2qyg@mail.gmail.com>
Subject: Re: [PATCH] media: mediatek: vcodec: avoid -Wcast-function-type-strict
 warning
To: Arnd Bergmann <arnd@kernel.org>
Cc: Minghsiu Tsai <minghsiu.tsai@mediatek.com>, Houlong Wei <houlong.wei@mediatek.com>, 
	Andrew-CT Chen <andrew-ct.chen@mediatek.com>, Mauro Carvalho Chehab <mchehab@kernel.org>, 
	Arnd Bergmann <arnd@arndb.de>, Matthias Brugger <matthias.bgg@gmail.com>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, 
	Tiffany Lin <tiffany.lin@mediatek.com>, Yunfei Dong <yunfei.dong@mediatek.com>, 
	Hans Verkuil <hverkuil-cisco@xs4all.nl>, 
	Nicolas Dufresne <nicolas.dufresne@collabora.com>, Alexandre Courbot <acourbot@chromium.org>, 
	Pi-Hsun Shih <pihsun@chromium.org>, linux-media@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, 
	linux-mediatek@lists.infradead.org
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Hi Arnd

Thanks for the patch

On Sat, Feb 24, 2024 at 1:11=E2=80=AFPM Arnd Bergmann <arnd@kernel.org> wro=
te:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> The ipi handler here tries hard to maintain const-ness of its argument,
> but by doing that causes a warning about function type casts:

I worked on the same issue, but in instead of removing the const, I
tried to constify everything:
https://patchwork.linuxtv.org/project/linux-media/patch/20240226-fix-clang-=
warnings-v2-3-fa1bc931d17e@chromium.org/

My main goal is to remove the warning, so any patch is OK for me ;)

>
> drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c:38:32: =
error: cast from 'mtk_vcodec_ipi_handler' (aka 'void (*)(void *, unsigned i=
nt, void *)') to 'ipi_handler_t' (aka 'void (*)(const void *, unsigned int,=
 void *)') converts to incompatible function type [-Werror,-Wcast-function-=
type-strict]
>    38 |         ipi_handler_t handler_const =3D (ipi_handler_t)handler;
>       |                                       ^~~~~~~~~~~~~~~~~~~~~~
>
> Remove the hack and just use a non-const argument.
>
> Fixes: bf1d556ad4e0 ("media: mtk-vcodec: abstract firmware interface")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/platform/mediatek/mdp/mtk_mdp_vpu.c      |  2 +-
>  .../mediatek/vcodec/common/mtk_vcodec_fw_vpu.c         | 10 +---------
>  drivers/media/platform/mediatek/vpu/mtk_vpu.c          |  2 +-
>  drivers/media/platform/mediatek/vpu/mtk_vpu.h          |  2 +-
>  4 files changed, 4 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_vpu.c b/drivers/=
media/platform/mediatek/mdp/mtk_mdp_vpu.c
> index b065ccd06914..378a1cba0144 100644
> --- a/drivers/media/platform/mediatek/mdp/mtk_mdp_vpu.c
> +++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_vpu.c
> @@ -26,7 +26,7 @@ static void mtk_mdp_vpu_handle_init_ack(const struct md=
p_ipi_comm_ack *msg)
>         vpu->inst_addr =3D msg->vpu_inst_addr;
>  }
>
> -static void mtk_mdp_vpu_ipi_handler(const void *data, unsigned int len,
> +static void mtk_mdp_vpu_ipi_handler(void *data, unsigned int len,
>                                     void *priv)
>  {
>         const struct mdp_ipi_comm_ack *msg =3D data;
> diff --git a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_=
vpu.c b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
> index 9f6e4b59455d..4c34344dc7dc 100644
> --- a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
> +++ b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
> @@ -29,15 +29,7 @@ static int mtk_vcodec_vpu_set_ipi_register(struct mtk_=
vcodec_fw *fw, int id,
>                                            mtk_vcodec_ipi_handler handler=
,
>                                            const char *name, void *priv)
>  {
> -       /*
> -        * The handler we receive takes a void * as its first argument. W=
e
> -        * cannot change this because it needs to be passed down to the r=
proc
> -        * subsystem when SCP is used. VPU takes a const argument, which =
is
> -        * more constrained, so the conversion below is safe.
> -        */
> -       ipi_handler_t handler_const =3D (ipi_handler_t)handler;
> -
> -       return vpu_ipi_register(fw->pdev, id, handler_const, name, priv);
> +       return vpu_ipi_register(fw->pdev, id, handler, name, priv);
>  }
>
>  static int mtk_vcodec_vpu_ipi_send(struct mtk_vcodec_fw *fw, int id, voi=
d *buf,
> diff --git a/drivers/media/platform/mediatek/vpu/mtk_vpu.c b/drivers/medi=
a/platform/mediatek/vpu/mtk_vpu.c
> index 7243604a82a5..724ae7c2ab3b 100644
> --- a/drivers/media/platform/mediatek/vpu/mtk_vpu.c
> +++ b/drivers/media/platform/mediatek/vpu/mtk_vpu.c
> @@ -635,7 +635,7 @@ int vpu_load_firmware(struct platform_device *pdev)
>  }
>  EXPORT_SYMBOL_GPL(vpu_load_firmware);
>
> -static void vpu_init_ipi_handler(const void *data, unsigned int len, voi=
d *priv)
> +static void vpu_init_ipi_handler(void *data, unsigned int len, void *pri=
v)
>  {
>         struct mtk_vpu *vpu =3D priv;
>         const struct vpu_run *run =3D data;
> diff --git a/drivers/media/platform/mediatek/vpu/mtk_vpu.h b/drivers/medi=
a/platform/mediatek/vpu/mtk_vpu.h
> index a56053ff135a..da05f3e74081 100644
> --- a/drivers/media/platform/mediatek/vpu/mtk_vpu.h
> +++ b/drivers/media/platform/mediatek/vpu/mtk_vpu.h
> @@ -17,7 +17,7 @@
>   * VPU interfaces with other blocks by share memory and interrupt.
>   */
>
> -typedef void (*ipi_handler_t) (const void *data,
> +typedef void (*ipi_handler_t) (void *data,
>                                unsigned int len,
>                                void *priv);
>
> --
> 2.39.2
>
>


--=20
Ricardo Ribalda