Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:5 as permitted sender) client-ip=2620:137:e000::3:5;
MIME-Version: 1.0
References: <20230807061115.3244501-1-victor.liu@nxp.com> <CACRpkdaGzXD6HbiX7mVUNJAJtMEPG00Pp6+nJ1P0JrfJ-ArMvQ@mail.gmail.com>
 <AM7PR04MB7046863700EA909289EAC17798B4A@AM7PR04MB7046.eurprd04.prod.outlook.com>
In-Reply-To: <AM7PR04MB7046863700EA909289EAC17798B4A@AM7PR04MB7046.eurprd04.prod.outlook.com>
From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Wed, 22 Nov 2023 14:58:30 +0100
Message-ID: <CACRpkdYPDi+TYj4Y89+iLKa__oFTuMKCPDB7UrVThEGd=6H3qw@mail.gmail.com>
Subject: Re: [PATCH v3] drm/bridge: panel: Add a device link between drm
 device and panel device
To:     Ying Liu <victor.liu@nxp.com>
Cc:     "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "andrzej.hajda@intel.com" <andrzej.hajda@intel.com>,
        "neil.armstrong@linaro.org" <neil.armstrong@linaro.org>,
        "rfoss@kernel.org" <rfoss@kernel.org>,
        "Laurent.pinchart@ideasonboard.com" 
        <Laurent.pinchart@ideasonboard.com>,
        "jonas@kwiboo.se" <jonas@kwiboo.se>,
        "jernej.skrabec@gmail.com" <jernej.skrabec@gmail.com>,
        "airlied@gmail.com" <airlied@gmail.com>,
        "daniel@ffwll.ch" <daniel@ffwll.ch>,
        Ulf Hansson <ulf.hansson@linaro.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Hi Ying,

On Mon, Nov 20, 2023 at 11:08=E2=80=AFAM Ying Liu <victor.liu@nxp.com> wrot=
e:

[Me]
> > > v2->v3:
> > > * Improve commit message s/swapped/reversed/.
> >
> > This patch causes a regression in the Ux500 MCDE
> > drivers/gpu/drm/mcde/* driver with the nt35510 panel
> > drivers/gpu/drm/panel/panel-novatek-nt35510.c
> > my dmesg looks like this:
(...)
> Sorry for the breakage and a bit late response(I'm a bit busy with intern=
al
> things).
>
> I think device_link_add() fails because a0351000.dsi.0 already depends
> on a0350000.mcde.  Can you confirm that device_link_add() returns NULL
> right after it calls device_is_dependent()?
>
> Does this patch fix the issue?

Yep it works!

You missed one device_link_del() instance on the errorpath.

Tested-by: Linus Walleij <linus.walleij@linaro.org>

Can you send it as a proper patch?

Yours,
Linus Walleij