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Message-ID: <33d5cc27-474b-fdec-a6b0-84ac16f7d386@redhat.com>
Date:   Thu, 22 Sep 2022 16:29:53 +0200
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Subject: Re: [PATCH -next 1/2] i2c: designware: Switch from using MMIO access
 to SMN access
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To:     Borislav Petkov <bp@suse.de>
Cc:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        "Limonciello, Mario" <mario.limonciello@amd.com>,
        =?UTF-8?B?SmFuIETEhWJyb8Wb?= <jsd@semihalf.com>,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        jarkko.nikula@linux.intel.com, wsa@kernel.org,
        rrangel@chromium.org, upstream@semihalf.com,
        Muralidhara M K <muralimk@amd.com>,
        Naveen Krishna Chatradhi <nchatrad@amd.com>
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 <c0c8bdce-26a0-ad3f-749b-7585d947608b@redhat.com> <YyxrdpUyc+kp48kX@zn.tnic>
From:   Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <YyxrdpUyc+kp48kX@zn.tnic>
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Hi,

On 9/22/22 16:04, Borislav Petkov wrote:
> On Thu, Sep 22, 2022 at 03:48:07PM +0200, Hans de Goede wrote:
>> Right, thank you for Cc-ing me. At least on X86 there are several platforms
>> (and 100-s of device models) which use a PMIC connected to the i2c-designware
>> controller and this PMIC gets poked directly from ACPI _S0 and _S3
>> (power on/off) methods. So the I2C bus driver needs to *bind* to the controller
>> as soon as we find its description in ACPI, otherwise we get a whole bunch
>> of failed ACPI OpRegion access errors as well as various actual really issues.
> 
> Thanks for explaining - I couldn't find the reason why it has to be a
> subsys_initcall.
> 
>> So please keep this as a subsys initcall.
> 
> Which means, init_amd_nbs() would have to be sorted to run before
> dw_i2c_init_driver()...

Yes if possible. One solution might be to make it a arch_initcall_sync()
which AFAIK runs after regular arch_initcall()-s but before subsys_initcall()-s.

Regards,

Hans