On Wed, Jul 13, 2022 at 11:41 PM Alexander Stein
[off-list ref] wrote:

Am Mittwoch, 13. Juli 2022, 02:45:06 CEST schrieb Saravana Kannan:

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On Wed, Jul 6, 2022 at 6:02 AM Alexander Stein
[off-list ref] wrote:


Thanks for testing all my patches and helping me debug this.

Btw, can you try to keep the subject the same please? Looks like
somewhere in your path [EXT] is added sometimes. lore.kernel.org keeps
the thread together, but my email client (gmail) gets confused.

Sorry about that. Unfortunately [EXT] is inserted automatically and it is
tedious and error-prone to remove it manually...

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Am Dienstag, 5. Juli 2022, 03:24:33 CEST schrieb Saravana Kannan:

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On Mon, Jul 4, 2022 at 12:07 AM Alexander Stein

[off-list ref] wrote:

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Am Freitag, 1. Juli 2022, 09:02:22 CEST schrieb Saravana Kannan:

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On Thu, Jun 30, 2022 at 11:02 PM Alexander Stein

[off-list ref] wrote:

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Hi Saravana,

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

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On Thu, Jun 23, 2022 at 5:08 AM Alexander Stein

[off-list ref] wrote:

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Hi,

Am Dienstag, 21. Juni 2022, 09:28:43 CEST schrieb Tony

Lindgren:

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Hi,

* Saravana Kannan [off-list ref] [700101 02:00]:

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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

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well BTW). Unfortunately the driver fails the same way:

Thanks for testing the patch!

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[    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:

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[    0.008160] irq: no irq domain found for gpc@303a0000 !

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.

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[    0.013251] Failed to map interrupt for
/soc@0/bus@30400000/timer@306a0000

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.

To clarify, you had the timer issue only with my "combine drivers"
patch,
right?

That's correct.

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The probe of imx8m-blk-ctrl got slightly delayed (from 0.74 to 0.90s
printk
time) but results in the identical error message.

My guess is that the probe attempt of blk-ctrl is delayed now till gpc
probes (because of the device links getting created with the
fwnode_dev_initialized() fix), but by the time gpc probe finishes, the
power domains aren't registered yet because of the additional level of
device addition and probing.

Can you try the attached patch please?

Sure, it needed some small fixes though. But the error still is present.

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And if that doesn't fix the issues, then enable the debug logs in the
following functions please and share the logs from boot till the
failure? If you can enable CONFIG_PRINTK_CALLER, that'd help too.
device_link_add()
fwnode_link_add()
fw_devlink_relax_cycle()

I switched fw_devlink_relax_cycle() for fw_devlink_relax_link() as the
former has no debug output here.

For the record I added the following line to my kernel command line:

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dyndbg="func device_link_add +p; func fwnode_link_add +p; func

fw_devlink_relax_link +p"

I attached the dmesg until the probe error to this mail. But I noticed the

following lines which seem interesting:

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[    1.466620][    T8] imx-pgc imx-pgc-domain.5: Linked as a consumer to
regulator.8
[    1.466743][    T8] imx-pgc imx-pgc-domain.5: imx_pgc_domain_probe:
Probe>

succeeded

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[    1.474733][    T8] imx-pgc imx-pgc-domain.6: Linked as a consumer to

regulator.9

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[    1.474774][    T8] imx-pgc imx-pgc-domain.6: imx_pgc_domain_probe:
Probe>

succeeded

I'm guessing this happens after the probe error.

Ok, I looked at the dmesg logs and this pretty much confirms my
thought on why the probe ordering wasn't maintained.

The power domains lack a compatible property, so the blk-ctrl is
linked as a consumer of the gpc instead:
[    0.343905][    T1] blk-ctrl@38320000 Linked as a fwnode consumer
to gpc@303a0000
[    0.343943][    T1] blk-ctrl@38320000 Linked as a fwnode consumer
to clock-controller@30380000
This ^^ is the device tree parsing figuring out the dependencies
between the DT nodes.

[    0.368462][    T1] platform 38320000.blk-ctrl: Linked as a
consumer to 30380000.clock-controller
[    0.368542][    T1] platform 38320000.blk-ctrl: Linked as a
consumer to 303a0000.gpc
This ^^ is converting the DT node dependencies into device links.

So, the only real options are:
1. Fix DT and add a compatible string to the DT nodes.
2. Move the initcall level of the regulator driver so the powerdomain
probe doesn't get deferred. Not ideal that we are playing initcall
chicken to handle the feature meant to remove the need for initcall
chicken. But I see these "device, but won't have a compatible
property" as exceptions and feel it's okay to have to play with
initcall levels to handle those.
3. Provide a helper function that driver that do this (creating
devices for child DT nodes without compatible property) can use to
move/copy their consumer device links to the child devices they add.
And then fix up the gpc driver so that it copies the gpc -- blk-ctrl
device link to the proper power domain.
4. I have another idea for how I could fix that at a driver core
level, but I'm not sure it'll work yet and its definitely not
something I want to try and get in for 5.19 -- too late for that IMHO.

Want to give (2) a shot so that I can still try to keep the cleanup
series that caused this problem (that's the long term goal) while I
give (3) and (4) a shot for 5.20?

Sure, I can give (2) a shot. Which initcall needs to be modified? You have a
diff snippet?

All initcall for all the regulator drivers that feed this gpc power domain.

BTW: this potentially affects all imx8m and imx7d as they have the same gpc
binding.

Good point. That's why I was asking for your help :) -- you have more
context on these hardware.

Can't say much about (1). I added Lucas Stach to recipients, he did a lot on
this gpc driver.
@Lucas: Do you have some input why the gpc power domains do not have a
compatible? Is it reasonable to add them?

It's generally frowned upon to update the kernel in a way that it
breaks backwards compatibility with an older DT binary. That's why I
didn't ask about (1).

It's fairly trivial to get it to work if we (who is "we" here?) agree
it's okay to add the compatible property and break DT backwards
compatibility in this case.

-Saravana