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

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Date:   Fri, 01 Jul 2022 08:01:56 +0200
From:   Alexander Stein <alexander.stein@...tq-group.com>
To:     Saravana Kannan <saravanak@...gle.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: (EXT) Re: [PATCH v2 1/9] PM: domains: Delete usage of driver_deferred_probe_check_state()

Hi Saravana,

Am Freitag, 1. Juli 2022, 02:37:14 CEST schrieb Saravana Kannan:
> 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?

I tried this patch and it delayed the driver initialization (those of UART as 
well BTW). Unfortunately the driver fails the same way:
> [    1.125253] imx8m-blk-ctrl 38320000.blk-ctrl: error -ENODEV: failed to 
attach power domain "bus"

More than that it even introduced some more errors:
> [    0.008160] irq: no irq domain found for gpc@...a0000 !
> [    0.013251] Failed to map interrupt for
> /soc@...us@...00000/timer@...a0000
> [    0.020152] Failed to initialize '/soc@...us@...00000/timer@...a0000':
> -22

I kept the timestamps to show that these errors happen very early. So now the 
usage of the "global" interrupt parent, set at line 18,
> interrupt-parent = <&gpc>;
is not possible at this point of boot time.

Best regards,
Alexander