linux-kernel - Re: [PATCH v1 06/10] device property: switch to use UUID API

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Message-ID: <20160218110754.GG1742@lahna.fi.intel.com>
Date:	Thu, 18 Feb 2016 13:07:54 +0200
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Theodore Ts'o <tytso@....edu>, Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	David Airlie <airlied@...ux.ie>,
	Benjamin Tissoires <benjamin.tissoires@...hat.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Mathias Nyman <mathias.nyman@...el.com>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Lv Zheng <lv.zheng@...el.com>, Mark Brown <broonie@...nel.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org, linux-efi@...r.kernel.org,
	linux-api@...r.kernel.org, linux-nvdimm@...ts.01.org
Subject: Re: [PATCH v1 06/10] device property: switch to use UUID API

On Wed, Feb 17, 2016 at 02:17:24PM +0200, Andy Shevchenko wrote:
> Switch to use a generic UUID API instead of custom approach. It allows to
> define UUIDs, compare them, and validate.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/acpi/property.c | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
> index 2aee416..1e75305 100644
> --- a/drivers/acpi/property.c
> +++ b/drivers/acpi/property.c
> @@ -25,15 +25,13 @@ static int acpi_data_get_property_array(struct acpi_device_data *data,
>  					const union acpi_object **obj);
>  
>  /* ACPI _DSD device properties UUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301 */
> -static const u8 prp_uuid[16] = {
> -	0x14, 0xd8, 0xff, 0xda, 0xba, 0x6e, 0x8c, 0x4d,
> -	0x8a, 0x91, 0xbc, 0x9b, 0xbf, 0x4a, 0xa3, 0x01
> -};
> +static const uuid_le prp_uuid =
> +	UUID_LE(0xdaffd814, 0x6eba, 0x4d8c,
> +		0x8a, 0x91, 0xbc, 0x9b, 0xbf, 0x4a, 0xa3, 0x01);
>  /* ACPI _DSD data subnodes UUID: dbb8e3e6-5886-4ba6-8795-1319f52a966b */
> -static const u8 ads_uuid[16] = {
> -	0xe6, 0xe3, 0xb8, 0xdb, 0x86, 0x58, 0xa6, 0x4b,
> -	0x87, 0x95, 0x13, 0x19, 0xf5, 0x2a, 0x96, 0x6b
> -};
> +static const uuid_le ads_uuid =
> +	UUID_LE(0xdbb8e3e6, 0x5886, 0x4ba6,
> +		0x87, 0x95, 0x13, 0x19, 0xf5, 0x2a, 0x96, 0x6b);

This looks better than the original but it is still not too readable.

I think it would be better to have uuid as string like:

static const char *ads_uuid = "dbb8e3e6-5886-4ba6-8795-1319f52a966b";

and then convert that to the right byte presentation when first time
used. That would match the uuid format in the ACPI (and device
properties) spec. and thus make it easier to read and understand.