linux-kernel - Re: [PATCH v2] ACPI: video: Handle fetching EDID as ACPI_TYPE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <492a990e-0af4-4acb-be4c-8821fceea2a0@amd.com>
Date: Mon, 31 Mar 2025 09:34:19 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
 Hans de Goede <hdegoede@...hat.com>, Gergo Koteles <soyer@....hu>
Cc: Len Brown <lenb@...nel.org>, Alex Hung <alex.hung@....com>,
 Rodrigo Siqueira <siqueira@...lia.com>,
 Alex Deucher <alexander.deucher@....com>, linux-acpi@...r.kernel.org,
 amd-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ACPI: video: Handle fetching EDID as ACPI_TYPE_PACKAGE

On 3/31/2025 08:23, Rafael J. Wysocki wrote:
> On Mon, Mar 31, 2025 at 3:04 PM Hans de Goede <hdegoede@...hat.com> wrote:
>>
>> Hi,
>>
>> On 31-Mar-25 1:46 PM, Rafael J. Wysocki wrote:
>>> On Fri, Mar 28, 2025 at 10:09 PM Gergo Koteles <soyer@....hu> wrote:
>>>>
>>>> The _DDC method should return a buffer, or an integer in case of an error.
>>>> But some Lenovo laptops incorrectly return EDID as buffer in ACPI package.
>>>>
>>>> Calling _DDC generates this ACPI Warning:
>>>> ACPI Warning: \_SB.PCI0.GP17.VGA.LCD._DDC: Return type mismatch - \
>>>> found Package, expected Integer/Buffer (20240827/nspredef-254)
>>>>
>>>> Use the first element of the package to get the EDID buffer.
>>>>
>>>> The DSDT:
>>>>
>>>> Name (AUOP, Package (0x01)
>>>> {
>>>>          Buffer (0x80)
>>>>          {
>>>>          ...
>>>>          }
>>>> })
>>>>
>>>> ...
>>>>
>>>> Method (_DDC, 1, NotSerialized)  // _DDC: Display Data Current
>>>> {
>>>>          If ((PAID == AUID))
>>>>          {
>>>>                  Return (AUOP) /* \_SB_.PCI0.GP17.VGA_.LCD_.AUOP */
>>>>          }
>>>>          ElseIf ((PAID == IVID))
>>>>          {
>>>>                  Return (IVOP) /* \_SB_.PCI0.GP17.VGA_.LCD_.IVOP */
>>>>          }
>>>>          ElseIf ((PAID == BOID))
>>>>          {
>>>>                  Return (BOEP) /* \_SB_.PCI0.GP17.VGA_.LCD_.BOEP */
>>>>          }
>>>>          ElseIf ((PAID == SAID))
>>>>          {
>>>>                  Return (SUNG) /* \_SB_.PCI0.GP17.VGA_.LCD_.SUNG */
>>>>          }
>>>>
>>>>          Return (Zero)
>>>> }
>>>>
>>>> Link: https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/Apx_B_Video_Extensions/output-device-specific-methods.html#ddc-return-the-edid-for-this-device
>>>> Cc: stable@...r.kernel.org
>>>> Fixes: c6a837088bed ("drm/amd/display: Fetch the EDID from _DDC if available for eDP")
>>>> Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4085
>>>> Signed-off-by: Gergo Koteles <soyer@....hu>
>>>> ---
>>>> Changes in v2:
>>>>   - Added comment
>>>>   - Improved commit message
>>>>   - Link to v1: https://lore.kernel.org/all/4cef341fdf7a0e877c50b502fc95ee8be28aa811.1743129387.git.soyer@irl.hu/
>>>
>>> Hans, any concerns here?
>>
>> No the patch looks good to me:
>>
>> Reviewed-by: Hans de Goede <hdegoede@...hat.com>
> 
> OK, applied as 6.15-rc material, thanks!

Sorry I'm a bit late to the party; but this looks good to me as well. 
Thanks Gergo for the solution!

Reviewed-by: Mario Limonciello <mario.limonciello@....com>