From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTP id 96B67AB3 for ; Wed, 14 May 2014 15:40:18 +0000 (UTC) Received: from mezzanine.sirena.org.uk (mezzanine.sirena.org.uk [106.187.55.193]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 5A32A20111 for ; Wed, 14 May 2014 15:40:17 +0000 (UTC) Date: Wed, 14 May 2014 16:40:02 +0100 From: Mark Brown To: Laurent Pinchart Message-ID: <20140514154002.GH12304@sirena.org.uk> References: <1872038.43ncqEMWSx@avalon> <1904209.2bUKgQ0eOo@vostro.rjw.lan> <20140514115745.GZ12304@sirena.org.uk> <7582809.t9iBxJcjvo@avalon> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="pzF0hARdObpE3ANG" Content-Disposition: inline In-Reply-To: <7582809.t9iBxJcjvo@avalon> Cc: ksummit-discuss@lists.linuxfoundation.org Subject: Re: [Ksummit-discuss] [TECH TOPIC] PM dependencies List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --pzF0hARdObpE3ANG Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, May 14, 2014 at 05:26:20PM +0200, Laurent Pinchart wrote: > On Wednesday 14 May 2014 12:57:45 Mark Brown wrote: > > Since the core device probe is deferred until everything it depends on > > is ready it'll get pushed along the device list so that it appears after > > everything it needs and hence is suspended first. > That might solve (part of) the master vs. components dependencies (and ev= en in=20 > that case I'm pretty sure that there will be cases where the master needs= to=20 > be suspended first and cases where th slave(s) need to be suspended first= ),=20 > but it doesn't handle inter-slaves dependencies. > In the V4L subsystem we've implemented an explicit power management API t= hat=20 > "slaves" (called subdevices in V4L) must implement, to be called by the= =20 > master. That's of course more of a workaround than a perfect (or even goo= d)=20 > solution. Right, that's what the function of the master device is in suspend for this model - it quiesces the compound device as a whole so that any interdependencies between the devices have been unwound (including giving callbacks to the slaves where appropriate). It gives us a place to hang everything associated with having the devices so closely interrelated. Though as Rafael says with async suspend that gets broken. --pzF0hARdObpE3ANG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJTc45PAAoJELSic+t+oim9WuUP/jiC6Rj3ZfH+P4pRyjUOMw+d qzP/45oqzQ3IkRGFgKo+0Z7XA322L4Cxnp6vHwO7pSI1oBQOj2xaWrHaLrOyqkwe n8GILLXxu1XTpvN/l4sI5208rVn3y3KBjUhgmLTHbCfHKsU5nNDyWGWZKFRb9VlY 043QbgwHuqtuHJXh6uOtDmKdSHj70y5ntf+Rc9wi5L44Hjtu0JseHuDsXJsa2Id9 XGRyOYSzyG6wMuAANq+mkesOkjS5OJ6b5sRPSHMcQaEp1CqAOYPIBQ9Ptrk4I00B bq6EsTUhzcFzsDq9edFIhvY/LZCN6ZRzvZeb3BNMCM6+pksffjL4FXHTKc2SSmf/ 0rm4nkyBHETEWZTBFTgWNhbVs8MiDJsWHPzpRF/+jnWU1/WIdmXcJ3h/XgxHO9tC KP3SUvOqyMd8m0+vj1mMfEmgtjhS6Xd7FBbs/UVsyUSeBNrJ2VyZtSLkUQJm1Jq+ DBxi56UtlR7Mn1l0DVGzIPJcfbQxaYPDan9tJcZgvTkHgvrbiHrMnIV/J4pdbo0K /HZI3aI8lNx+X+2ibs6Adc284eCCo4Go0U1GuwtzP16I8FSeG+zCB6z+tJNX6UMz Iu4iOJuVnqTjHDr64AlFhtoBwTwMP3nPPr7qXxPRMqZpDXkgprN8XHQA4O72r33L pcgARdZAa9uq2dGlsFXx =tk/n -----END PGP SIGNATURE----- --pzF0hARdObpE3ANG--