From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: efi/reboot: Fall back to original power-off method if EFI_RESET_SHUTDOWN returns Date: Thu, 22 Jun 2017 12:04:30 +0200 Message-ID: <099b3f68-46b1-201c-065f-cf5c4bdcc528@redhat.com> References: <20170423123655.13015-1-hdegoede@redhat.com> <430d6ff2-264a-80f8-24e0-0d9af4377844@redhat.com> <20170622095517.GA3238@codeblueprint.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:43582 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752188AbdFVKEd (ORCPT ); Thu, 22 Jun 2017 06:04:33 -0400 In-Reply-To: <20170622095517.GA3238@codeblueprint.co.uk> Content-Language: en-US Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matt Fleming Cc: Len Brown , Ard Biesheuvel , Andy Shevchenko , linux-acpi@vger.kernel.org, Peter Jones , linux-efi@vger.kernel.org, Mark Salter Hi, On 22-06-17 11:55, Matt Fleming wrote: > On Wed, 21 Jun, at 03:15:09PM, Hans de Goede wrote: >> HI, >> >> On 23-04-17 14:36, Hans de Goede wrote: >>> Commit 44be28e9dd98 ("x86/reboot: Add EFI reboot quirk for ACPI Hardware >>> Reduced flag") sets pm_power_off to efi_power_off() when the >>> acpi_gbl_reduced_hardware flag is set. >>> >>> According to its commit message this is necessary because: "BayTrail-T >>> class of hardware requires EFI in order to powerdown and reboot and no >>> other reliable method exists" >>> >>> But I have a Bay Trail CR tablet where the EFI_RESET_SHUTDOWN call does >>> not work, it simply returns without doing anything (AFAICT). >>> >>> So it seems that some Bay Trail devices must use EFI for power-off, while >>> for others only ACPI works. >>> >>> Note that efi_power_off() only gets used if the platform code defines >>> efi_poweroff_required() and that returns true, this currently only ever >>> happens on x86. >>> >>> Since on the devices which need ACPI for power-off the EFI_RESET_SHUTDOWN >>> call simply returns, this patch makes the efi-reboot code remember the >>> old pm_power_off handler and if EFI_RESET_SHUTDOWN returns it falls back >>> to calling that. >>> >>> This seems preferable to dmi-quirking our way out of this, since there >>> are likely quite a few devices suffering from this. >>> >>> Cc: Mark Salter >>> Signed-off-by: Hans de Goede >> >> What is the status of this patch ? It has had 2 somewhat favorable >> reviews and then things went silent ? > > Sorry about the delay. I've picked this up for the efi-next branch > since we're at -rc6 and it doesn't look like an -rc6-urgent bug. Ack, putting this in -next is the right thing to do, you never know what weird firmware quirks this patch may trigger. E.g. EFI_RESET_SHUTDOWN could return on some models with the PMIC turned off leaving the device running for XX ms on its power-supply capacitors, and then calling into the ACPI method may cause weirdness. Regards, Hans