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References: <20231123032615.3760488-1-victor.liu@nxp.com>
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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Sat, 25 Nov 2023 00:48:34 +0100
Message-ID: <CACRpkdZsqR0MUoLdmdk1-XW0zQDTf0g+-dp1hsSzQ2vXosKoXA@mail.gmail.com>
Subject: Re: [PATCH] drm/bridge: panel: Check device dependency before
 managing device link
To:     Liu Ying <victor.liu@nxp.com>
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        andrzej.hajda@intel.com, neil.armstrong@linaro.org,
        rfoss@kernel.org, Laurent.pinchart@ideasonboard.com,
        jonas@kwiboo.se, jernej.skrabec@gmail.com,
        maarten.lankhorst@linux.intel.com, mripard@kernel.org,
        tzimmermann@suse.de, airlied@gmail.com, daniel@ffwll.ch,
        angelogioacchino.delregno@collabora.com, ulf.hansson@linaro.org
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On Thu, Nov 23, 2023 at 4:22=E2=80=AFAM Liu Ying <victor.liu@nxp.com> wrote=
:

> Some panel devices already depend on DRM device, like the panel in
> arch/arm/boot/dts/st/ste-ux500-samsung-skomer.dts, because DRM device is
> the ancestor of those panel devices.  device_link_add() would fail by
> returning a NULL pointer for those panel devices because of the existing
> dependency.  So, check the dependency by calling device_is_dependent()
> before adding or deleting device link between panel device and DRM device
> so that the link is managed only for independent panel devices.
>
> Fixes: 887878014534 ("drm/bridge: panel: Fix device link for DRM_BRIDGE_A=
TTACH_NO_CONNECTOR")
> Fixes: 199cf07ebd2b ("drm/bridge: panel: Add a device link between drm de=
vice and panel device")
> Reported-by: Linus Walleij <linus.walleij@linaro.org>
> Closes: https://lore.kernel.org/lkml/CACRpkdaGzXD6HbiX7mVUNJAJtMEPG00Pp6+=
nJ1P0JrfJ-ArMvQ@mail.gmail.com/T/
> Tested-by: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Liu Ying <victor.liu@nxp.com>

Patch applied to drm-misc-fixes.

Yours,
Linus Walleij