linux-kernel - Re: [PATCH 1/6] 8250/Kconfig: add config option CONFIG_SERIAL_8250

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Message-ID: <20160106104602.GA19507@pd.tnic>
Date:	Wed, 6 Jan 2016 11:46:02 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	"Wang, Annie" <Annie.Wang@....com>
Cc:	Andy Shevchenko <andy.shevchenko@...il.com>,
	Vinod Koul <vinod.koul@...el.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	"dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
	"Huang, Ray" <Ray.Huang@....com>,
	"Wan, Vincent" <Vincent.Wan@....com>, "Xue, Ken" <Ken.Xue@....com>,
	Robin Murphy <robin.murphy@....com>,
	Graeme Gregory <gg@...mlogic.co.uk>,
	"Li, Tony" <Tony.Li@....com>,
	"Yu, Xiangliang" <Xiangliang.Yu@....com>
Subject: Re: [PATCH 1/6] 8250/Kconfig: add config option
 CONFIG_SERIAL_8250_AMD

On Wed, Jan 06, 2016 at 02:08:18AM +0000, Wang, Annie wrote:
> How about I add select ARM_AMBA and SERIAL_8250 in arch/x86/Kconfig?

Yeah, select sounds good in that case, except in that particular case ...

> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index db3622f..0fe6657 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -537,11 +537,15 @@ config X86_AMD_PLATFORM_DEVICE
>         depends on ACPI
>         select COMMON_CLK
>         select PINCTRL
> +       select SERIAL_8250
> +       select ARM_AMBA

... that's a X86_AMD_PLATFORM_DEVICE which selects ARM thing? i.e.,
ARM_AMBA. Can that even work?

[ Rant on the side: And that ARM_AMBA thing has, of course, no effing
  help text. Dammit, people need to start explaining those cryptic
  abbreviations. Somewhere in the code I found "Advanced Microcontroller
  Bus Architecture". This is clearly suboptimal. ]

So why does the X86 platform device need to select the AMBA crap?

>         ---help---
>           Select to interpret AMD specific ACPI device to platform device
>           such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
>           I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
> -         implemented under PINCTRL subsystem.
> +         implemented under PINCTRL subsystem. Carrizo's UART is implemented
> +         under SERIAL_8250. Carrizo's UART DMA device is an amba device,
> +         it selects ARM_AMBA option.

As I already said before, please refrain from using platform names like
Carrizo because people have no clue what those are. Only the marketing
people do. Use CPU family + models instead.

> CPU_SUP_AMD is only configured in X86 arch. AMD future  ARM64 processors may
> also need acpi to platform support.

So this code is going to be shared between X86 and ARM64?

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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