linux-kernel - Re: [RFC PATCH v2 06/10] spi: add support for ACPI reconfigure notifications

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Message-ID: <CAE1zotJ1FKNdxCqV_XRUJrFB-fqHpBr54rj3C65ZM80h7=t3DQ@mail.gmail.com>
Date:	Wed, 4 May 2016 18:04:45 +0300
From:	Octavian Purdila <octavian.purdila@...el.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Wolfram Sang <wsa@...-dreams.de>,
	Joel Becker <jlbec@...lplan.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	linux-efi@...r.kernel.org, linux-i2c <linux-i2c@...r.kernel.org>,
	linux-spi <linux-spi@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Irina Tirdea <irina.tirdea@...el.com>
Subject: Re: [RFC PATCH v2 06/10] spi: add support for ACPI reconfigure notifications

On Tue, May 3, 2016 at 3:19 PM, Mark Brown <broonie@...nel.org> wrote:
> On Thu, Apr 28, 2016 at 10:37:57PM +0300, Octavian Purdila wrote:
>> On Thu, Apr 28, 2016 at 8:42 PM, Mark Brown <broonie@...nel.org> wrote:
>
>> > There's more code here now than I remember but this all looks *really*
>> > close to the DT code except for the OF_POPULATED flag that we set when
>> > things are instantiated in DT.  The duplication seems bad but the fact
>> > that we're missing the flag worries me...  do we have guarantees that
>> > ACPI won't double register?
>
>> We use the adev->flags.visited to check when a device has been already
>> enumerated, and we skip registering a new SPI slave in that case.
>
> OK, but the fact that I need to know that isn't exactly thrilling -
> that's really the issue with the not quite duplication here.  It's not
> just if the code works but also the maintainability.

I agree that this is unfortunate. I could not find a common path for
both device tree and ACPI. Perhaps when we remove of_node from struct
device and move to fwnode we could remove some duplication.

I can add a couple of comments around  acpi_device_enumerated() and
adev->flags.visited = true; to make it clear that we won't double
enumerate. Will that help?