linux-kernel - Re: [PATCH v8 8/8] clk: Add KUnit tests for clks registered with struct clk_parent

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Message-ID: <6f5a5b5f-71a7-4ed3-8cb3-d930bbce599b@linuxfoundation.org>
Date: Fri, 27 Sep 2024 14:45:47 -0600
From: Shuah Khan <skhan@...uxfoundation.org>
To: Guenter Roeck <linux@...ck-us.net>, Stephen Boyd <sboyd@...nel.org>
Cc: Michael Turquette <mturquette@...libre.com>,
 linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
 patches@...ts.linux.dev, kunit-dev@...glegroups.com,
 linux-kselftest@...r.kernel.org, devicetree@...r.kernel.org,
 Brendan Higgins <brendan.higgins@...ux.dev>, David Gow
 <davidgow@...gle.com>, Rae Moar <rmoar@...gle.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 "Rafael J . Wysocki" <rafael@...nel.org>, Rob Herring <robh@...nel.org>,
 Saravana Kannan <saravanak@...gle.com>, Daniel Latypov
 <dlatypov@...gle.com>, Christian Marangi <ansuelsmth@...il.com>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>, Maxime Ripard <maxime@...no.tech>,
 Geert Uytterhoeven <geert+renesas@...der.be>,
 Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH v8 8/8] clk: Add KUnit tests for clks registered with
 struct clk_parent_data

On 9/27/24 10:19, Guenter Roeck wrote:
> Copying devicetree maintainers.
> 
> On Thu, Sep 26, 2024 at 09:39:38PM -0700, Guenter Roeck wrote:
>> On Thu, Sep 26, 2024 at 09:14:11PM -0700, Guenter Roeck wrote:
>>> Hi Stephen,
>>>
>>> On Thu, Jul 18, 2024 at 02:05:07PM -0700, Stephen Boyd wrote:
>>>> Test that clks registered with 'struct clk_parent_data' work as
>>>> intended and can find their parents.
>>>>
>>>
>>> When testing this on arm64, I see the error below. The error is only
>>> seen if I boot through efi, i.e., with "-bios QEMU_EFI-aarch64.fd"
>>> qemu parameter.
>>>
>>> Any idea what might cause the problem ?
>>>
>> I noticed that the new overlay tests fail as well, also with "path '/' not
>> found".
>>
>> [Maybe] answering my own question: I think the problem may be that there
>> is no devicetree file and thus no devicetree root when booting through
>> efi (in other words, of_root is NULL). Would it make sense to skip the
>> tests in that case ?
>>
> 
> The problem is that of_root is not initialized in arm64 boots if ACPI
> is enabled.
> 
>  From arch/arm64/kernel/setup.c:setup_arch():
> 
> 	if (acpi_disabled)
> 		unflatten_device_tree();		// initializes of_root
> 
> ACPI is enabled if the system boots from EFI. This also affects
> CONFIG_OF_KUNIT_TEST, which explicitly checks if of_root exists and
> fails the test if it doesn't.
> 
> I think those tests need to add a check for this condition, or affected
> machines won't be able to run those unit tests. The obvious solution would
> be to check if of_root is set, but then the associated test case in
> CONFIG_OF_KUNIT_TEST would not make sense.
> 
> Any suggestions ?
> 

Would it work if these tests check if acpi_disabled and skip if it isn't
disabled? It might be low overhead condition to check from these tests.

acpi_disabled is exported:

arch/arm64/kernel/acpi.c:EXPORT_SYMBOL(acpi_disabled);
arch/loongarch/kernel/acpi.c:EXPORT_SYMBOL(acpi_disabled);
arch/riscv/kernel/acpi.c:EXPORT_SYMBOL(acpi_disabled);
arch/x86/kernel/acpi/boot.c:EXPORT_SYMBOL(acpi_disabled);

thanks,
-- Shuah