linux-kernel - Re: [PATCH v1 0/6] ACPI: scan: MIPI DiSco for Imaging support

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Date:   Fri, 9 Jun 2023 19:31:53 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH v1 0/6] ACPI: scan: MIPI DiSco for Imaging support

Hi Sakari,

On Fri, Jun 9, 2023 at 11:51 AM Sakari Ailus
<sakari.ailus@...ux.intel.com> wrote:
>
> Hi Rafael,
>
> On Wed, May 24, 2023 at 08:06:09PM +0200, Rafael J. Wysocki wrote:
> > On Wed, May 24, 2023 at 1:48 PM Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> > >
> > > Hi Folks,
> > >
> > > This basically is a re-write of a recent patch series from Sakari:
> > >
> > > https://lore.kernel.org/linux-acpi/20230329100951.1522322-1-sakari.ailus@linux.intel.com
> > >
> > > The general idea is the same - CSI-2 resource descriptors, introduced in
> > > ACPI 6.4 and defined by
> > >
> > > https://uefi.org/specs/ACPI/6.5/06_Device_Configuration.html#camera-serial-interface-csi-2-connection-resource-descriptor
> > >
> > > are found and used for creating a set of software nodes that represent the CSI-2
> > > connection graph.
> > >
> > > These software nodes need to be available before any scan handlers or ACPI drivers
> > > are bound to any struct acpi_device objects, so all of that is done at the early
> > > stage of ACPI device enumeration, but unnecessary ACPI namespace walks are avoided.
> > >
> > > The CSI-2 software nodes are populated with data extracted from the CSI-2 resource
> > > descriptors themselves and from device properties defined by the MIPI DiSco for
> > > Imaging specification (see https://www.mipi.org/specifications/mipi-disco-imaging).
> > >
> > > Patches [4,6/6] come from the original series directly, but the other patches have
> > > been changes substantially, so I've decided to re-start patch series versioning from
> > > scratch.
> > >
> > > This series is based on the patch at
> > >
> > > https://patchwork.kernel.org/project/linux-acpi/patch/12223415.O9o76ZdvQC@kreacher/
> > >
> > > applied on top of 6.4-rc3.
> > >
> > > Later on, I'll put all of this material into a special git branch for easier
> > > access.
> >
> > The patches are now available from the acpi-mipi-disco-imaging branch
> > in the linux-pm.git tree at kernel.org.
>
> I've been doing some testing on this version.

Thanks for testing!

> It oopses and that's relatively easy to fix by removing the kfree() that
> releases memory of the software nodes and properties.

It would be good to check which of the patches introduces the crash.

> It doesn't work with that change either, it would seem like that the _CRS
> CSI2 data is (most of the time) released before it gets used for creating
> the software nodes, leading node registration to fail. This appears to be
> taking place in different processes --- there's a work queue.
>
> Moving the release of the _CRS CSI-2 resources to where they are no longer
> needed makes the system crash early at boot. I've yet to debug this
> further.

OK, thanks!

I think that the way to go would be to check if the results of the
first patch are as expected and if so, move to the next one etc.