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Message-ID: <b350fd1e60cc0fa24a81be512e35f9b6a2358f94.camel@redhat.com>
Subject: Re: [PATCH] drm/nouveau/disp: Revert a NULL check inside
 nouveau_connector_get_modes
From:   Lyude Paul <lyude@redhat.com>
To:     Karol Herbst <kherbst@redhat.com>, linux-kernel@vger.kernel.org
Cc:     Ben Skeggs <bskeggs@redhat.com>, dri-devel@lists.freedesktop.org,
        nouveau@lists.freedesktop.org, Olaf Skibbe <news@kravcenko.com>
Date:   Mon, 07 Aug 2023 16:32:53 -0400
In-Reply-To: <20230805101813.2603989-1-kherbst@redhat.com>
References: <20230805101813.2603989-1-kherbst@redhat.com>
Organization: Red Hat Inc.
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Ugh, thanks for catching this!

Reviewed-by: Lyude Paul <lyude@redhat.com>

On Sat, 2023-08-05 at 12:18 +0200, Karol Herbst wrote:
> The original commit adding that check tried to protect the kenrel against
> a potential invalid NULL pointer access.
>=20
> However we call nouveau_connector_detect_depth once without a native_mode
> set on purpose for non LVDS connectors and this broke DP support in a few
> cases.
>=20
> Cc: Olaf Skibbe <news@kravcenko.com>
> Cc: Lyude Paul <lyude@redhat.com>
> Closes: https://gitlab.freedesktop.org/drm/nouveau/-/issues/238
> Closes: https://gitlab.freedesktop.org/drm/nouveau/-/issues/245
> Fixes: 20a2ce87fbaf8 ("drm/nouveau/dp: check for NULL nv_connector->nativ=
e_mode")
> Signed-off-by: Karol Herbst <kherbst@redhat.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_connector.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/dr=
m/nouveau/nouveau_connector.c
> index f75c6f09dd2af..a2e0033e8a260 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_connector.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
> @@ -967,7 +967,7 @@ nouveau_connector_get_modes(struct drm_connector *con=
nector)
>  	/* Determine display colour depth for everything except LVDS now,
>  	 * DP requires this before mode_valid() is called.
>  	 */
> -	if (connector->connector_type !=3D DRM_MODE_CONNECTOR_LVDS && nv_connec=
tor->native_mode)
> +	if (connector->connector_type !=3D DRM_MODE_CONNECTOR_LVDS)
>  		nouveau_connector_detect_depth(connector);
> =20
>  	/* Find the native mode if this is a digital panel, if we didn't

--=20
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat