From mboxrd@z Thu Jan 1 00:00:00 1970 From: mjg59@srcf.ucam.org (Matthew Garrett) Date: Tue, 26 Nov 2013 14:45:32 +0000 Subject: ACPI In-Reply-To: References: <20131125154110.GB3243@srcf.ucam.org> Message-ID: <20131126144532.GA10641@srcf.ucam.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Nov 26, 2013 at 01:43:40PM +0100, Linus Walleij wrote: > On Mon, Nov 25, 2013 at 4:41 PM, Matthew Garrett wrote: > > > In the past ACPI implementations handled GPIO by providing > > methods that accessed hardware registers directly. I've seen DSDTs that > > implement i2c entirely in ASL. > > Is that common? No, thankfully. > Since i2c is a slow bus, can be 100kHz or so, how does that > avoid locking the entire CPU while e.g. waiting for transactions on > the external bus to complete? Check status register, interruptible sleep, repeat until done. > I have a feeling we should not recommend ARM implementers > to go and do things like this. Oh, absolutely. -- Matthew Garrett | mjg59 at srcf.ucam.org