linux-kernel - Re: [PATCH v2 1/9] PM: domains: Delete usage of driver_deferred_probe_check

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Date:   Thu, 30 Jun 2022 17:37:14 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Alexander Stein <alexander.stein@...tq-group.com>
Cc:     Tony Lindgren <tony@...mide.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>, kernel-team@...roid.com,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        iommu@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-gpio@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH v2 1/9] PM: domains: Delete usage of driver_deferred_probe_check_state()

On Thu, Jun 23, 2022 at 5:08 AM Alexander Stein
<alexander.stein@...tq-group.com> wrote:
>
> Hi,
>
> Am Dienstag, 21. Juni 2022, 09:28:43 CEST schrieb Tony Lindgren:
> > Hi,
> >
> > * Saravana Kannan <saravanak@...gle.com> [700101 02:00]:
> > > Now that fw_devlink=on by default and fw_devlink supports
> > > "power-domains" property, the execution will never get to the point
> > > where driver_deferred_probe_check_state() is called before the supplier
> > > has probed successfully or before deferred probe timeout has expired.
> > >
> > > So, delete the call and replace it with -ENODEV.
> >
> > Looks like this causes omaps to not boot in Linux next. With this
> > simple-pm-bus fails to probe initially as the power-domain is not
> > yet available. On platform_probe() genpd_get_from_provider() returns
> > -ENOENT.
> >
> > Seems like other stuff is potentially broken too, any ideas on
> > how to fix this?
>
> I think I'm hit by this as well, although I do not get a lockup.
> In my case I'm using arch/arm64/boot/dts/freescale/imx8mq-tqma8mq-mba8mx.dts
> and probing of 38320000.blk-ctrl fails as the power-domain is not (yet)
> registed.

Ok, took a look.

The problem is that there are two drivers for the same device and they
both initialize this device.

    gpc: gpc@...a0000 {
        compatible = "fsl,imx8mq-gpc";
    }

$ git grep -l "fsl,imx7d-gpc" -- drivers/
drivers/irqchip/irq-imx-gpcv2.c
drivers/soc/imx/gpcv2.c

IMHO, this is a bad/broken design.

So what's happening is that fw_devlink will block the probe of
38320000.blk-ctrl until 303a0000.gpc is initialized. And it stops
blocking the probe of 38320000.blk-ctrl as soon as the first driver
initializes the device. In this case, it's the irqchip driver.

I'd recommend combining these drivers into one. Something like the
patch I'm attaching (sorry for the attachment, copy-paste is mangling
the tabs). Can you give it a shot please?

-Saravana

Download attachment "0001-combine-drivers.patch" of type "application/x-patch" (3528 bytes)