From mboxrd@z Thu Jan 1 00:00:00 1970 From: Magnus Damm Subject: Re: [patch update] Re: [linux-pm] Run-time PM idea (was: Re: [RFC][PATCH 0/2] PM: Rearrange core suspend code) Date: Thu, 11 Jun 2009 14:27:26 +0900 Message-ID: References: <200906102331.14267.rjw@sisk.pl> <200906110115.30729.oliver@neukum.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from yw-out-2324.google.com ([74.125.46.29]:8885 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753432AbZFKF1Z convert rfc822-to-8bit (ORCPT ); Thu, 11 Jun 2009 01:27:25 -0400 In-Reply-To: <200906110115.30729.oliver@neukum.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Oliver Neukum Cc: "Rafael J. Wysocki" , Alan Stern , Linux-pm mailing list , ACPI Devel Maling List , LKML On Thu, Jun 11, 2009 at 8:15 AM, Oliver Neukum wrote= : > Am Mittwoch, 10. Juni 2009 23:31:13 schrieb Rafael J. Wysocki: >> > > +/** >> > > + * pm_check_children - Check if all children of a device have b= een >> > > suspended. + * @dev: Device to check. >> > > + * >> > > + * Returns 0 if all children of the device have been suspended = or >> > > -EBUSY + * otherwise. >> > > + */ >> > >> > We might want to do a runtime suspend even if the device's childre= n >> > aren't already suspended. =A0For example, you could suspend a link= while >> > leaving the device on the other end of the link at full power -- >> > especially if powering down the device is slow but changing the li= nk's >> > power level is fast. >> >> Well, this means that the dependencies between devices in the device= tree >> are pretty much useless for the run-time PM as far as the core is >> concerned. =A0In which case, why did you mention them at all? > > Some bussystems need this constraint others don't or only for some no= des. > We need a way to communicate this to the core. I agree that this depends on the bus. Our SuperH on-chip SoC platform devices are arranged in a flat fashion so no real problem there, but if there whould be dependencies then I think we need to manage it recursively somehow. Compare that to PM of our I2C driver and the I2C bus hanging off from that. In that case I'd like to be able to autosuspend the I2C master driver regardless of the I2C slave devices and their PM state. / magnus -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760927AbZFKF1e (ORCPT ); Thu, 11 Jun 2009 01:27:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755608AbZFKF10 (ORCPT ); Thu, 11 Jun 2009 01:27:26 -0400 Received: from yw-out-2324.google.com ([74.125.46.29]:8885 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753432AbZFKF1Z convert rfc822-to-8bit (ORCPT ); Thu, 11 Jun 2009 01:27:25 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=m4vauLUtNIN6BNDhJTnK7e4DpZ8t5dpHLV7z/fakR+jHzHJH5wlHJKpPgnz1mnCaOk VjphvceArJOEokXo1vI7bIhdWamofcoAFhfJ/XJHOvRFP6Io8VfB3ZS/nGaKDcCJ3LA6 F/TuuIFiT7cuba2j7RM+4Nu1TaRZpc94S/Mc8= MIME-Version: 1.0 In-Reply-To: <200906110115.30729.oliver@neukum.org> References: <200906102331.14267.rjw@sisk.pl> <200906110115.30729.oliver@neukum.org> Date: Thu, 11 Jun 2009 14:27:26 +0900 Message-ID: Subject: Re: [patch update] Re: [linux-pm] Run-time PM idea (was: Re: [RFC][PATCH 0/2] PM: Rearrange core suspend code) From: Magnus Damm To: Oliver Neukum Cc: "Rafael J. Wysocki" , Alan Stern , Linux-pm mailing list , ACPI Devel Maling List , LKML Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 11, 2009 at 8:15 AM, Oliver Neukum wrote: > Am Mittwoch, 10. Juni 2009 23:31:13 schrieb Rafael J. Wysocki: >> > > +/** >> > > + * pm_check_children - Check if all children of a device have been >> > > suspended. + * @dev: Device to check. >> > > + * >> > > + * Returns 0 if all children of the device have been suspended or >> > > -EBUSY + * otherwise. >> > > + */ >> > >> > We might want to do a runtime suspend even if the device's children >> > aren't already suspended.  For example, you could suspend a link while >> > leaving the device on the other end of the link at full power -- >> > especially if powering down the device is slow but changing the link's >> > power level is fast. >> >> Well, this means that the dependencies between devices in the device tree >> are pretty much useless for the run-time PM as far as the core is >> concerned.  In which case, why did you mention them at all? > > Some bussystems need this constraint others don't or only for some nodes. > We need a way to communicate this to the core. I agree that this depends on the bus. Our SuperH on-chip SoC platform devices are arranged in a flat fashion so no real problem there, but if there whould be dependencies then I think we need to manage it recursively somehow. Compare that to PM of our I2C driver and the I2C bus hanging off from that. In that case I'd like to be able to autosuspend the I2C master driver regardless of the I2C slave devices and their PM state. / magnus