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

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Message-ID: <CAJZ5v0hy7ge+vPgNXzo89=qu7pP-tPgbjUPRHUMdwUnSTpVXQQ@mail.gmail.com>
Date: Mon, 31 Mar 2025 15:23:28 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Hans de Goede <hdegoede@...hat.com>, Gergo Koteles <soyer@....hu>
Cc: Len Brown <lenb@...nel.org>, Alex Hung <alex.hung@....com>, 
	Mario Limonciello <mario.limonciello@....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 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!