From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH 2/2] ACPI / osi: add DMI quirk for Dell systems Date: Mon, 05 Feb 2018 16:15:00 +0200 Message-ID: <1517840100.22495.25.camel@linux.intel.com> References: <1517388005-14852-1-git-send-email-alex.hung@canonical.com> <1517388005-14852-2-git-send-email-alex.hung@canonical.com> <20180205141447.6e1442ac@endymion> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mga01.intel.com ([192.55.52.88]:34484 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753107AbeBEOPH (ORCPT ); Mon, 5 Feb 2018 09:15:07 -0500 In-Reply-To: <20180205141447.6e1442ac@endymion> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Jean Delvare , Alex Hung Cc: rjw@rjwysocki.net, lenb@kernel.org, gregkh@linuxfoundation.org, davem@davemloft.net, mika.westerberg@linux.intel.com, f.fainelli@gmail.com, dmitry.torokhov@gmail.com, kishon@ti.com, karniksayli1995@gmail.com, linux-acpi@vger.kernel.org, Mario.Limonciello@dell.com On Mon, 2018-02-05 at 14:14 +0100, Jean Delvare wrote: > On Wed, 31 Jan 2018 00:40:05 -0800, Alex Hung wrote: > > A number of Dell systems require an OEM _OSI string "Linux-Dell- > > Video" as > > a BIOS workaround for a system hang bug caused by discrete VGA. The > > form of > > the OEM _OSI string is discussed in Documentation/acpi/osi.txt and > > is > > defined by each OEM. > > I admit I don't understand how it is the operating system's job to > carry the information from the BIOS to the BIOS. > > + for (i = 0; i < OSI_STRING_ENTRIES_MAX; i++) { > > + osi = &osi_setup_entries[i]; > > + if (!strcmp(osi->string, str)) { > > This can only happen if the user passes acpi_osi=Linux-Dell-Video or > acpi_osi=!Linux-Dell-Video on the boot command line, right? > > > + osi->enable = true; > > Does this not prevent the user from explicitly disabling it with > acpi_osi=!Linux-Dell-Video ? Playing with OSI string is a bad idea. I wouldn't do anything while Rafael, or even Len can confirm that is the right thing to do. For me, AFAIK we need to be bug-to-bug compatible with Windows (at least on ACPICA side), so, what Windows exactly does on such laptops? -- Andy Shevchenko Intel Finland Oy