Re: [PATCH v4 1/8] drm/rockchip: vop2: Switch impossible format conditional to WARN_ON

From: David Laight <david.laight.linux@gmail.com>
To: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Cc: "Sandy Huang" <hjc@rock-chips.com>,
	"Heiko Stübner" <heiko@sntech.de>,
	"Andy Yan" <andy.yan@rock-chips.com>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"David Airlie" <airlied@gmail.com>,
	"Simona Vetter" <simona@ffwll.ch>,
	"Chaoyi Chen" <chaoyi.chen@rock-chips.com>,
	dri-devel@lists.freedesktop.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org,
	"Daniel Stone" <daniels@collabora.com>,
	kernel@collabora.com
Subject: Re: [PATCH v4 1/8] drm/rockchip: vop2: Switch impossible format conditional to WARN_ON
Date: Thu, 11 Dec 2025 22:38:22 +0000	[thread overview]
Message-ID: <20251211223822.6eeabb4d@pumpkin> (raw)
In-Reply-To: <20251211-vop2-atomic-fixups-v4-1-5d50eda26bf8@collabora.com>

On Thu, 11 Dec 2025 21:40:31 +0100
Nicolas Frattaroli <nicolas.frattaroli@collabora.com> wrote:

> From: Daniel Stone <daniels@collabora.com>
> 
> We should never be able to create a framebuffer with an unsupported
> format, so throw a warning if this ever happens, instead of attempting
> to stagger on.

It doesn't look like you've changed the behaviour.
Except that all the systems with PANIC_ON_WARN set will panic.
I believe that is somewhere over 90% of systems.

	David

> 
> Signed-off-by: Daniel Stone <daniels@collabora.com>
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
> ---
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> index 498df0ce4680..20b49209ddcd 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> @@ -1030,7 +1030,8 @@ static int vop2_plane_atomic_check(struct drm_plane *plane,
>  		return 0;
>  
>  	format = vop2_convert_format(fb->format->format);
> -	if (format < 0)
> +	/* We shouldn't be able to create a fb for an unsupported format */
> +	if (WARN_ON(format < 0))
>  		return format;
>  
>  	/* Co-ordinates have now been clipped */
> 