> -----Original Message----- > From: Andy Shevchenko [mailto:andriy.shevchenko@xxxxxxxxxxxxxxx] > Sent: Monday, February 5, 2018 8:15 AM > To: Jean Delvare <jdelvare@xxxxxxx>; Alex Hung <alex.hung@xxxxxxxxxxxxx> > Cc: rjw@xxxxxxxxxxxxx; lenb@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; > davem@xxxxxxxxxxxxx; mika.westerberg@xxxxxxxxxxxxxxx; f.fainelli@xxxxxxxxx; > dmitry.torokhov@xxxxxxxxx; kishon@xxxxxx; karniksayli1995@xxxxxxxxx; linux- > acpi@xxxxxxxxxxxxxxx; Limonciello, Mario <Mario_Limonciello@xxxxxxxx> > Subject: Re: [PATCH 2/2] ACPI / osi: add DMI quirk for Dell systems > > 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? > The issue that's being worked around isn't an ACPICA interpreter issue, but it's a graphics device configuration issue. Windows expects to use RTD3 on the NVIDIA GPU but Linux drivers don't. It leads to system hangs on the Linux side. ��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
