linux-kernel - Re: [PATCH v3 01/11] ACPI: delay enumeration of devices with a

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Date:   Mon, 11 Oct 2021 12:30:41 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Mark Gross <markgross@...nel.org>,
        Andy Shevchenko <andy@...radead.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Daniel Scally <djrscally@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Len Brown <lenb@...nel.org>,
        linux-acpi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Kate Hsuan <hpa@...hat.com>, linux-media@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v3 01/11] ACPI: delay enumeration of devices with a _DEP
 pointing to an INT3472 device

On Mon, Oct 11, 2021 at 09:11:05AM +0200, Hans de Goede wrote:
> Hi,
> 
> On 10/11/21 8:19 AM, Mika Westerberg wrote:
> > Hi,
> > 
> > On Sun, Oct 10, 2021 at 08:56:57PM +0200, Hans de Goede wrote:
> >> +/* List of HIDs for which we honor deps of matching ACPI devs, when checking _DEP lists. */
> >> +static const char * const acpi_honor_dep_ids[] = {
> >> +	"INT3472", /* Camera sensor PMIC / clk and regulator info */
> > 
> > Is there some reason why we can't do this for all devices with _DEP?
> > That way we don't need to maintain lists like this.
> 
> Up until now the ACPI core deliberate mostly ignores _DEP-s because the
> _DEP method may point to pretty much any random ACPI object and Linux does
> not necessarily have a driver for all ACPI objects the driver points too,
> which would lead to the devices never getting instantiated.
> 
> In hindsight this might not have been the best solution (1), but if we
> now start honoring _DEP-s for all devices all of a sudden then this
> will almost certainly lead to a whole bunch of regressions.
> 
> Note that in this case the HID which triggers this is for the device
> being depended upon and for all camera sensors used with the IPU3 and
> IPU4 Intel camera blocks this is the INT3472 device. By triggering on
> this HID (rather then on the sensor HIDs) I expect that we will not
> need to update this list all that often.

I see and agree. Thanks for the explanation!

No objections from my side then :)