From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Cameron Subject: Re: [PATCH 6/7] iio: mlx90614: Add power management Date: Thu, 12 Mar 2015 10:30:27 +0000 Message-ID: <55016AC3.2060704@kernel.org> References: <1424879712-28304-1-git-send-email-vianney.leclement@essensium.com> <1424879712-28304-7-git-send-email-vianney.leclement@essensium.com> <54FDBEB7.8030403@kernel.org> <20150309164308.GA2320@katana> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20150309164308.GA2320@katana> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: =?UTF-8?B?Vmlhbm5leSBsZSBDbMOpbWVudCBkZSBTYWludC1NYXJjcQ==?= , linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Peter Meerwald , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Arnout Vandecappelle (Essensium/Mind)" , Linux I2C , Wolfram Sang List-Id: devicetree@vger.kernel.org On 09/03/15 16:43, Wolfram Sang wrote: > On Mon, Mar 09, 2015 at 03:39:35PM +0000, Jonathan Cameron wrote: >> On 25/02/15 15:55, Vianney le Cl=C3=A9ment de Saint-Marcq wrote: >>> Add support for system sleep and runtime power management. >>> >>> To wake up the device, the SDA line should be held low for at least= 33ms >>> while SCL is high. As this is not possible using the i2c API (and = not >>> supported by all i2c adapters), a GPIO connected to the SDA line is >>> needed. The GPIO is named "wakeup" and can be specified in a devic= e >>> tree with the "wakeup-gpios" binding. >> Needs some i2c specialist input on this! As you mentioned it is lia= ble >> to be controversial. Wolfram, is this a one off special or do >> any other devices do this sort of magic? >=20 > s/magic/insanity/ :) >=20 > I have never heard of something like this. Unsuprisingly, I can > not recommend doing it this way. But we all know hardware... >=20 > And while we could think about reusing the bus_recovery_infrastructur= e, > I don't think it is worth the hazzle. So, doing this GPIO fallback ma= y > well be the best we can do now. >=20 =46air enough. Lets go with this approach then and hope this is the on= ly bit of hardware ever to do this (yeah right ;)