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

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: linux-efi@vger.kernel.org, David Airlie <airlied@linux.ie>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	dri-devel@lists.freedesktop.org,
	Benjamin Tissoires <benjamin.tissoires@redhat.com>,
	Lv Zheng <lv.zheng@intel.com>,
	Matt Fleming <matt@codeblueprint.co.uk>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-nvdimm@lists.01.org, linux-acpi@vger.kernel.org,
	Zhang Rui <rui.zhang@intel.com>,
	Mathias Nyman <mathias.nyman@intel.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Mark Brown <broonie@kernel.org>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Theodore Ts'o <tytso@mit.edu>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v1 06/10] device property: switch to use UUID API
Date: Fri, 26 Feb 2016 16:28:10 +0200	[thread overview]
Message-ID: <1456496890.13244.146.camel@linux.intel.com> (raw)
In-Reply-To: <20160218110754.GG1742@lahna.fi.intel.com>

On Thu, 2016-02-18 at 13:07 +0200, Mika Westerberg wrote:
> 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@linux.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.

Yes we can do this on slow paths. Or in cases where we know that
conversion happens only once.

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

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