Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755858Ab3G3Nyj (ORCPT ); Tue, 30 Jul 2013 09:54:39 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:47466 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754396Ab3G3Nyh (ORCPT ); Tue, 30 Jul 2013 09:54:37 -0400 From: "Rafael J. Wysocki" To: Aaron Lu Cc: ACPI Devel Maling List , LKML , Linux PM list , Yinghai Lu , Bjorn Helgaas , Tejun Heo , linux-ide@vger.kernel.org Subject: Re: [PATCH 1/3] ACPI / PM: Only set power states of devices that are power manageable Date: Tue, 30 Jul 2013 16:04:47 +0200 Message-ID: <1738639.5UcWLydKxR@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.10.0+; KDE/4.9.5; x86_64; ; ) In-Reply-To: <51F6FE34.2020703@intel.com> References: <10433383.dueoNg39qi@vostro.rjw.lan> <3386345.rYEkrXssx8@vostro.rjw.lan> <51F6FE34.2020703@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2587 Lines: 59 On Tuesday, July 30, 2013 07:43:48 AM Aaron Lu wrote: > On 07/30/2013 06:21 AM, Rafael J. Wysocki wrote: > > On Monday, July 29, 2013 10:09:53 PM Aaron Lu wrote: > >> On 07/27/2013 09:10 PM, Rafael J. Wysocki wrote: > >>> From: Rafael J. Wysocki > >>> > >>> Make acpi_device_set_power() check if the given device is power > >>> manageable before checking if the given power state is valid for that > >>> device. Otherwise it will print that "Device does not support" that > >>> power state into the kernel log, which may not make sense for some > >>> power states (D0 and D3cold are supported by all devices by > >>> definition). > >> > >> It will not print "Device does not support" that power state if that > >> power state is D0 or D3cold since we have unconditionally set those two > >> power state's valid flag. > > > > So you didn't actually looked at acpi_bus_get_power_flags() that set the > > power.states[].flags.valid flag, because If you had looked at it, you would > > have seen that that's not the case. > > > > No, we don't set the valid flag for devices that aren't power manageable > > (i.e. have flags.power_manageable unset), which is the *whole* *point* of > > this change. > > Right, I missed this. Sorry for the noise. > > > > >> OTOH, what value should we return for a device node that is not power > >> manageable in acpi_device_set_power when the target state is D0 or D3 > >> cold? The old behavior is to return 0, meanning success without taking > >> any actual action. > >> > >> In acpi_bus_set_power, if the device is not power manageable, we will > >> return -ENODEV; in acpi_dev_pm_full/low_power, we will return 0 as in > >> the original acpi_device_set_power. So return -EINVAL here is correct? > > > > No, the original acpi_device_set_power() will return -ENODEV then, but > > in my opinion returning -EINVAL is more accurate, because "power > > manageable" means "you can change power state of it". > > Shall I prepare a patch to update the errno in acpi_bus_set_power? In fact, it doesn't need to check flags.power_manageable after this patch and the debug message won't be missed I think, so please just remove the whole if () from there, if that's not a problem. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/