From mboxrd@z Thu Jan 1 00:00:00 1970 From: liam.r.girdwood@linux.intel.com (Liam Girdwood) Date: Mon, 11 Aug 2014 10:59:45 +0100 Subject: [alsa-devel] [PATCH] ASoC: rt286: Add API to set supported jack type In-Reply-To: <20140807173136.GN17528@sirena.org.uk> References: <1407217970-20126-1-git-send-email-bardliao@realtek.com> <20140806205421.GZ17528@sirena.org.uk> <20140807173136.GN17528@sirena.org.uk> Message-ID: <1407751185.2487.150.camel@loki> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, 2014-08-07 at 18:31 +0100, Mark Brown wrote: > On Thu, Aug 07, 2014 at 01:43:24AM +0000, Bard Liao wrote: > > > > If this is coming from the hardware design I'd expect this to be configured > > > via platform data or firmware data rather than with an API. > > > Why do it this way? > > > Actually, this patch is for Intel platform which doesn't support platform data > > yet. That's why we create an API so they can call the API in machine driver. > > So, this is something that the people wanting to use ACPI in platforms > with devices like this are going to have to deal with - we need a way of > getting configuration to devices. Traditionally small tweaks have been > done based on DMI information but that's not at all scalable. I believe > newer ACPI specs are trying to accomodate this due to the expanding > range of systems supporting ACPI. Punting to the machine driver just > moves the problem around, it doesn't really address it. > Unfortunately this will be needed for some Broadwell based BIOSes since the timing of the ACPI spec/implementation has meant that some Broadwell BIOSes will contain the data whilst most others wont atm :( > I've CCed in Graeme Gregory who's been writing some guidelines for this > sort of thing in the context of ARMv8 serviers - the most recent patch > is: > > http://thread.gmane.org/gmane.linux.acpi.devel/69757 > > The advice there looks good to me - see the "Device Enumeration" > section. This is indeed good, just too late for the initial Broadwell BIOSes that wont have this _DSD field for the codec (it will be hard coded for Windows anyway). Liam