Re: [PATCH 2/2] ACPI / osi: add DMI quirk for Dell systems

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Mon, Feb 05, 2018 at 05:36:18PM +0000, Mario.Limonciello@dell.com wrote:
> > -----Original Message-----
> > From: Andy Shevchenko [mailto:andriy.shevchenko@linux.intel.com]
> > Sent: Monday, February 5, 2018 8:15 AM
> > To: Jean Delvare <jdelvare@suse.de>; Alex Hung <alex.hung@canonical.com>
> > 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; Limonciello, Mario <Mario_Limonciello@Dell.com>
> > 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.

Can we adjust Linux drivers to do the right thing? Or is it regarding
the binary NVIDIA blob?

Thanks.

-- 
Dmitry