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

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Message-ID: <20170522105602.c7tfkjoepkesmxcb@dell>
Date:   Mon, 22 May 2017 11:56:02 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] mfd: axp20x-i2c: Document that this must be
 builtin on x86

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.

> ---
> 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/

> +	  I2C_DESIGNWARE_PLATFORM and I2C_DESIGNWARE_BAYTRAIL must be 'y' too.
> +
>  config MFD_AXP20X_RSB
>  	tristate "X-Powers AXP series PMICs with RSB"
>  	select MFD_AXP20X

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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