linux-kernel - Re: [PATCH v4 2/2] mfd: axp20x-i2c: Document that this must be builtin on x86

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Message-ID: <bbe96039-b4da-32be-1d77-05b3e0b344f5@redhat.com>
Date:   Fri, 26 May 2017 13:14:22 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     linux-kernel@...r.kernel.org, Chen-Yu Tsai <wens@...e.org>
Subject: Re: [PATCH v4 2/2] mfd: axp20x-i2c: Document that this must be
 builtin on x86

Hi,

On 22-05-17 12:56, Lee Jones wrote:
> On Mon, 15 May 2017, Hans de Goede wrote:
> 
>> On x86 the axp288 PMIC provides an ACPI OpRegion handler, which must be
>> available before other drivers using it are loaded, which can only be
>> ensured if the mfd, OpRegionr and i2c-bus drivers are built in.
>>
>> Since the axp20x mfd code is used on non X86 too we cannot simply change
>> this into a bool, I've tried some Kconfig magic with if x86 but I could
>> not get this working correctly, so this commit just documents that this
>> should be builtin on x86, which fixes errors like these during boot:
>>
>> mmc0: SDHCI controller on ACPI [80860F14:00] using ADMA
>> ACPI Error: No handler for Region [REGS] (ffff93543b0cc3a8) [UserDefinedRegion]
>> ACPI Error: Region UserDefinedRegion (ID=143) has no handler (20170119/exfldio-2
>> ACPI Error: Method parse/execution failed [\_SB.PCI0.I2C7.PMI5.GET] (Node ffff93
>> ACPI Error: Method parse/execution failed [\_SB.PCI0.SHC1._PS0] (Node ffff93543b
>> acpi 80860F14:02: Failed to change power state to D0
>>
>> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> 
> Would be good to get an Ack by the users/maintainers of this driver.

If you look at recent commits to drivers for the mfd-subdevices for the AXP288
(which is the only AXP PMIC found on x86 systems) you will see that I've
been the only one touch them / caring about them and in many cases fixing
them from being non-functional to actually working.

I do have quite a few people who are using the AXP288 code on Bay and Cherry
Trail devices with this PMIC and who have send me thank you's and test
success reports.

So I guess I'm the closest thing to a MAINTAINER for the axp288 bits of
this driver.

>> ---
>> Changes in v2:
>> -Fix Kconfig depends and selects to fix warning reported by kbuild test robot
>> -Improve commit msg (add example of ACPI errors this avoids)
>> Changes in v3:
>> -Since the axp20x mfd code is used on ARM too where it does not necessarily
>>   need to be builtin settle for simply documenting the need to have this
>>   builtin on x86
>> ---
>>   drivers/mfd/Kconfig | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>> index 61ebda81e134..cfac1e8a0a20 100644
>> --- a/drivers/mfd/Kconfig
>> +++ b/drivers/mfd/Kconfig
>> @@ -160,6 +160,11 @@ config MFD_AXP20X_I2C
>>   	  components like regulators or the PEK (Power Enable Key) under the
>>   	  corresponding menus.
>>   
>> +	  Note on x86 this provides an ACPI OpRegion, so this must be 'y'
>> +	  (builtin) and not a module, as the OpRegion must be available as
>> +	  soon as possible. For the same reason the i2c bus driver options
> 
> Nit: s/i2c/I2C/

Fixed for v5 (which I will send in a minute).

Regards,

Hans