Re: (EXT) Re: [PATCH v2 1/9] PM: domains: Delete usage of driver_deferred_probe_check_state()

Alexander Stein
2022-07-01T06:02:10Z

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@ew.tq-group.com> wrote:
> > Hi,
> >
> > Am Dienstag, 21. Juni 2022, 09:28:43 CEST schrieb Tony Lindgren:
> > > Hi,
> > >
> > > * Saravana Kannan <saravanak@google.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@303a0000 {
> 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@303a0000 !
> [ 0.013251] Failed to map interrupt for
> /soc@0/bus@30400000/timer@306a0000
> [ 0.020152] Failed to initialize '/soc@0/bus@30400000/timer@306a0000':
> -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