Date:   Mon, 04 Jul 2022 09:07:48 +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: (EXT) Re: [PATCH v2 1/9] PM: domains: Delete usage of driver_deferred_probe_check_state()

Am Freitag, 1. Juli 2022, 09:02:22 CEST schrieb Saravana Kannan:
> On Thu, Jun 30, 2022 at 11:02 PM Alexander Stein
> 
> <alexander.stein@...tq-group.com> wrote:
> > 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:
> Thanks for testing the patch!
> 
> > > [    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 !
> 
> So the idea behind my change was that as long as the irqchip isn't the
> root of the irqdomain (might be using the terms incorrectly) like the
> gic, you can make it a platform driver. And I was trying to hack up a
> patch that's the equivalent of platform_irqchip_probe() (which just
> ends up eventually calling the callback you use in IRQCHIP_DECLARE().
> I probably made some mistake in the quick hack that I'm sure if
> fixable.
> 
> > > [    0.013251] Failed to map interrupt for
> > > /soc@...us@...00000/timer@...a0000
> 
> However, this timer driver also uses TIMER_OF_DECLARE() which can't
> handle failure to get the IRQ (because it's can't -EPROBE_DEFER). So,
> this means, the timer driver inturn needs to be converted to a
> platform driver if it's supposed to work with the IRQCHIP_DECLARE()
> being converted to a platform driver.
> 
> But that's a can of worms not worth opening. But then I remembered
> this simpler workaround will work and it is pretty much a variant of
> the workaround that's already in the gpc's irqchip driver to allow two
> drivers to probe the same device (people really should stop doing
> that).
> 
> Can you drop my previous hack patch and try this instead please? I'm
> 99% sure this will work.
> 
> diff --git a/drivers/irqchip/irq-imx-gpcv2.c
> b/drivers/irqchip/irq-imx-gpcv2.c index b9c22f764b4d..8a0e82067924 100644
> --- a/drivers/irqchip/irq-imx-gpcv2.c
> +++ b/drivers/irqchip/irq-imx-gpcv2.c
> @@ -283,6 +283,7 @@ static int __init imx_gpcv2_irqchip_init(struct
> device_node *node,
>          * later the GPC power domain driver will not be skipped.
>          */
>         of_node_clear_flag(node, OF_POPULATED);
> +       fwnode_dev_initialized(domain->fwnode, false);
>         return 0;
>  }

Just to be sure here, I tried this patch on top of next-20220701 but 
unfortunately this doesn't fix the original problem either. The timer errors 
are gone though.
The probe of imx8m-blk-ctrl got slightly delayed (from 0.74 to 0.90s printk 
time) but results in the identical error message.

Best regards,
Alexander

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