linux-kernel - Re: [PATCH 1/4] ACPI: OSI: Remove Linux-Dell-Video

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Message-ID: <CAAd53p6MfBaRTTNJ5mAFU6XfDndLFJihLHKdrbq8Nq-27LArjg@mail.gmail.com>
Date:   Wed, 24 Aug 2022 22:16:30 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     rafael@...nel.org, Len Brown <lenb@...nel.org>,
        nouveau@...ts.freedesktop.org, hdegoede@...hat.com,
        ddadap@...dia.com, Dell.Client.Kernel@...l.com, kherbst@...hat.com,
        Lyude Paul <lyude@...hat.com>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] ACPI: OSI: Remove Linux-Dell-Video _OSI string

On Wed, Aug 24, 2022 at 2:51 AM Mario Limonciello
<mario.limonciello@....com> wrote:
>
> This string was introduced because drivers for NVIDIA hardware
> had bugs supporting RTD3 in the past.  Thoes bugs have been fixed
> by commit 5775b843a619 ("PCI: Restore config space on runtime resume
> despite being unbound"). so vendors shouldn't be using this string
> to modify ASL anymore.

Add some backgrounds on what happened.

Before proprietary NVIDIA driver supports RTD3, Ubuntu has a mechanism
that can switch PRIME on and off, though it requires to logout/login
to make the library switch happen.
When the PRIME is off, the mechanism unload NVIDIA driver and put the
device to D3cold, but GPU never came back to D0 again. So ODM use the
_OSI to expose an old _DSM method to switch the power on/off.

The issue is fixed by the said commit so we can discard the workaround now.

Kai-Heng

>
> Reviewed-by: Lyude Paul <lyude@...hat.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  drivers/acpi/osi.c | 9 ---------
>  1 file changed, 9 deletions(-)
>
> diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
> index 9f6853809138..c2f6b2f553d9 100644
> --- a/drivers/acpi/osi.c
> +++ b/drivers/acpi/osi.c
> @@ -44,15 +44,6 @@ osi_setup_entries[OSI_STRING_ENTRIES_MAX] __initdata = {
>         {"Processor Device", true},
>         {"3.0 _SCP Extensions", true},
>         {"Processor Aggregator Device", true},
> -       /*
> -        * Linux-Dell-Video is used by BIOS to disable RTD3 for NVidia graphics
> -        * cards as RTD3 is not supported by drivers now.  Systems with NVidia
> -        * cards will hang without RTD3 disabled.
> -        *
> -        * Once NVidia drivers officially support RTD3, this _OSI strings can
> -        * be removed if both new and old graphics cards are supported.
> -        */
> -       {"Linux-Dell-Video", true},
>         /*
>          * Linux-Lenovo-NV-HDMI-Audio is used by BIOS to power on NVidia's HDMI
>          * audio device which is turned off for power-saving in Windows OS.
> --
> 2.34.1
>