From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH] acpi: Fall back to manually changing SCI_EN Date: Wed, 28 Apr 2010 20:58:20 +0200 Message-ID: <201004282058.20910.rjw@sisk.pl> References: <1271711614-15527-1-git-send-email-mjg@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-2" Content-Transfer-Encoding: 7bit Return-path: Received: from ogre.sisk.pl ([217.79.144.158]:53136 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754263Ab0D1S57 (ORCPT ); Wed, 28 Apr 2010 14:57:59 -0400 In-Reply-To: <1271711614-15527-1-git-send-email-mjg@redhat.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett , lenb@kernel.org Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, pm list , Len Brown On Monday 19 April 2010, Matthew Garrett wrote: > The ACPI spec tells us that the ACPI SCI_EN bit is under hardware control > and shouldn't be touched by the OS. It seems that the Leading Other OS > ignores this and some machines expect this behaviour. We have a blacklist > for these, but given that we're able to detect the failure case and the > alternative to breaking the spec is letting the machine crash and burn, > let's try falling back when we know the alternative is a mostly-dead > machine. > > Signed-off-by: Matthew Garrett I guess we can try that, but I'd prefer it if that went into .35. It _should_ be safe, but ... Anyway, Acked-by: Rafael J. Wysocki > --- > drivers/acpi/sleep.c | 16 +++++++++++++--- > 1 files changed, 13 insertions(+), 3 deletions(-) > > diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c > index f74834a..79df8d4 100644 > --- a/drivers/acpi/sleep.c > +++ b/drivers/acpi/sleep.c > @@ -227,6 +227,7 @@ static int acpi_suspend_begin(suspend_state_t pm_state) > static int acpi_suspend_enter(suspend_state_t pm_state) > { > acpi_status status = AE_OK; > + acpi_status enable_status = AE_OK; > unsigned long flags = 0; > u32 acpi_state = acpi_target_sleep_state; > > @@ -254,10 +255,19 @@ static int acpi_suspend_enter(suspend_state_t pm_state) > } > > /* If ACPI is not enabled by the BIOS, we need to enable it here. */ > - if (set_sci_en_on_resume) > + if (!set_sci_en_on_resume) > + enable_status = acpi_enable(); > + > + if (set_sci_en_on_resume || enable_status == AE_NO_HARDWARE_RESPONSE) > + /* If we're still in legacy mode then we have a problem. The > + * spec tells us that this bit is under hardware control, but > + * there's no plausible way that the OS can transition back to > + * legacy mode so our choices here are to either ignore the > + * spec or crash and burn horribly. The latter doesn't seem > + * like it's ever going to be the preferable choice, so let's > + * live dangerously. > + */ > acpi_write_bit_register(ACPI_BITREG_SCI_ENABLE, 1); > - else > - acpi_enable(); > > /* Reprogram control registers and execute _BFS */ > acpi_leave_sleep_state_prep(acpi_state);