From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH 6/7] iio: mlx90614: Add power management Date: Mon, 9 Mar 2015 17:43:08 +0100 Message-ID: <20150309164308.GA2320@katana> 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> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="huq684BweRXVnRxX" Return-path: Content-Disposition: inline In-Reply-To: <54FDBEB7.8030403-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sender: linux-iio-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jonathan Cameron Cc: Vianney le =?utf-8?Q?Cl=C3=A9ment?= de Saint-Marcq , 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 --huq684BweRXVnRxX Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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. > >=20 > > 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 device > > tree with the "wakeup-gpios" binding. > Needs some i2c specialist input on this! As you mentioned it is liable > to be controversial. Wolfram, is this a one off special or do > any other devices do this sort of magic? s/magic/insanity/ :) I have never heard of something like this. Unsuprisingly, I can not recommend doing it this way. But we all know hardware... And while we could think about reusing the bus_recovery_infrastructure, I don't think it is worth the hazzle. So, doing this GPIO fallback may well be the best we can do now. --huq684BweRXVnRxX Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJU/c2cAAoJEBQN5MwUoCm2FkIP/3FI5LL0CgAzQFo6q2fy08yr Ee1m2xBWD5rlT8oDtYRrAPq+cz5NU8tvwpxjUiIGwb2D/Gn7F+nCWu4GKFUJ7f48 041ifDquYqpkfsT5sIILWn2mDJJX7w0KEIF7h/VGoaVSmWTE7UZnrkvk2DKp7lbO ZStvhynJ2QNhzETcBcADstwCw/6yq3iEYGAJrqapclUrNkIkicQL27Em6nVdGavY 9WaGbew2MwJSMKoyAtzrX5jE/LJKfxbtYncLCR0YucPvmQzrB2PyZzZh42HbftqH NmNrAQJnFyGOKRCHISyoscM0WnNcbjPhUWlPRWVaQrgUbRQd67jhDUfj5IYxQpnY oKKca60h2GagHPGpGo6Lpu0l5yJk8bVDpl281M12S5IWhd/XtH3qEMfcVndcejTl 90Z8EwBMwFozg9KFFxtMbXa3CHpGeIEKoKuzhYbNsl3fj4gKwjsfgTphlWUzB2DE tBdB6DFdEy3BrJBNBpyAgQXFxGa76zPR25rlhA5k3G62mHMbtKhzpGiYw4D9mlxP dmVN3aJWT6aMNQtcla2OPfaiI1sX8OXee+HX20b5G0GglStc429iBg4oVfyIukV6 xYJBo8AIATNIe0TMvhnykGTtN7QAvmlxRWSIXxG1nRWa7aPppYL0KfHs3SgUZmi9 e21m/ivCI/w3JvEpGQe/ =GMGj -----END PGP SIGNATURE----- --huq684BweRXVnRxX--