6.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Gergo Koteles soyer@irl.hu
commit ebca08fef88febdb0a898cefa7c99b9e25b3a984 upstream.
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-... Cc: stable@vger.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@irl.hu Reviewed-by: Hans de Goede hdegoede@redhat.com Reviewed-by: Mario Limonciello mario.limonciello@amd.com Link: https://patch.msgid.link/61c3df83ab73aba0bc7a941a443cd7faf4cf7fb0.1743195250... Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/acpi/acpi_video.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -648,6 +648,13 @@ acpi_video_device_EDID(struct acpi_video
obj = buffer.pointer;
+ /* + * Some buggy implementations incorrectly return the EDID buffer in an ACPI package. + * In this case, extract the buffer from the package. + */ + if (obj && obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 1) + obj = &obj->package.elements[0]; + if (obj && obj->type == ACPI_TYPE_BUFFER) { *edid = kmemdup(obj->buffer.pointer, obj->buffer.length, GFP_KERNEL); ret = *edid ? obj->buffer.length : -ENOMEM; @@ -657,7 +664,7 @@ acpi_video_device_EDID(struct acpi_video ret = -EFAULT; }
- kfree(obj); + kfree(buffer.pointer); return ret; }