Received-SPF: pass (google.com: domain of linux-kernel+bounces-211534-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Precedence: bulk
MIME-Version: 1.0
References: <988e48090982c89ce0c906954832fdfb09a1ce34.camel@sapience.com>
 <20240528084413.2624435-1-sakari.ailus@linux.intel.com> <a05df025-a0be-49cd-84a9-7d7fb2eeb33e@redhat.com>
 <e9062095-b312-44df-a9e3-0b09f3ec9eff@redhat.com> <4b387b4d-f778-4891-9f07-df5fc0a093cd@redhat.com>
 <ZmmQLt7wB-yGQBTw@kekkonen.localdomain> <CAJZ5v0ii3WFQRPdfHeeW4M9kXSWDVxxxy02zThcf25mjNwqDAw@mail.gmail.com>
 <ZmmT56Cyvb2FCyav@kekkonen.localdomain> <CAJZ5v0hOBggQR_=uA3VuhruQnZihVxHHovpTz4=qfcbiSunsYw@mail.gmail.com>
 <ZmmY3he9vfWVWU3I@kekkonen.localdomain>
In-Reply-To: <ZmmY3he9vfWVWU3I@kekkonen.localdomain>
From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Wed, 12 Jun 2024 15:06:53 +0200
Message-ID: <CAJZ5v0j7HTfg1wY+B+7vhE6tBKPVHMuu_MsFHjaLK70VS_cNEw@mail.gmail.com>
Subject: Re: [PATCH 1/1] ACPI: scan: Ignore Dell XPS 9320 camera graph port nodes
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>, Hans de Goede <hdegoede@redhat.com>, 
	Genes Lists <lists@sapience.com>, linux-kernel@vger.kernel.org, mchehab@kernel.org, 
	hverkuil-cisco@xs4all.nl, laurent.pinchart@ideasonboard.com, 
	wentong.wu@intel.com, linux-media@vger.kernel.org, linux-acpi@vger.kernel.org, 
	"regressions@lists.linux.dev" <regressions@lists.linux.dev>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Hi Sakari,

On Wed, Jun 12, 2024 at 2:47=E2=80=AFPM Sakari Ailus
<sakari.ailus@linux.intel.com> wrote:
>
> Hi Rafael,
>
> On Wed, Jun 12, 2024 at 02:32:26PM +0200, Rafael J. Wysocki wrote:
> > > > > > I just hit the same problem on another Dell laptop. It seems th=
at
> > > > > > all Dell laptops with IPU6 camera from the Tiger Lake, Alder La=
ke
> > > > > > and Raptor Lake generations suffer from this problem.
> > > > > >
> > > > > > So instead of playing whack a mole with DMI matches we should
> > > > > > simply disable ACPI MIPI DISCO support on all Dell laptops
> > > > > > with those CPUs. I'm preparing a fix for this to replace
> > > > > > the DMI matching now.
> > > > >
> > > > > DisCo for Imaging support shouldn't be dropped on these systems, =
and this
> > > > > isn't what your patch does either. Instead the ACPI graph port no=
des (as
> > > > > per Linux specific definitions) are simply dropped, i.e. this isn=
't related
> > > > > to DisCo for Imaging at all.
> > > >
> > > > So it looks like the changelog of that patch could be improved, rig=
ht?
> > >
> > > Well, yes. The reason the function is in the file is that nearly all =
camera
> > > related parsing is located there, not that it would be related to Dis=
Co for
> > > Imaging as such.
> >
> > So IIUC the camera graph port nodes are created by default with the
> > help of the firmware-supplied information, but if that is defective a
> > quirk can be added to skip the creation of those ports in which case
> > they will be created elsewhere.
> >
> > Is this correct?
>
> Yes.

So it would be good to add a comment to this effect to
acpi_nondev_subnode_extract() where acpi_graph_ignore_port() is
called.

And there is a somewhat tangential question that occurred to me: If
the nodes are created elsewhere when acpi_graph_ignore_port() is true,
why is it necessary to consult the platform firmware for the
information on them at all?  Wouldn't it be better to simply always
create them elsewhere?