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(2001-1c00-0c32-7800-5bfa-a036-83f0-f9ec.cable.dynamic.v6.ziggo.nl. [2001:1c00:c32:7800:5bfa:a036:83f0:f9ec]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5edcaac38f4sm4949440a12.10.2025.03.31.06.03.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Mar 2025 06:03:54 -0700 (PDT) Message-ID: Date: Mon, 31 Mar 2025 15:03:52 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] ACPI: video: Handle fetching EDID as ACPI_TYPE_PACKAGE To: "Rafael J. Wysocki" , Gergo Koteles Cc: Len Brown , Alex Hung , Mario Limonciello , Rodrigo Siqueira , Alex Deucher , linux-acpi@vger.kernel.org, amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <61c3df83ab73aba0bc7a941a443cd7faf4cf7fb0.1743195250.git.soyer@irl.hu> Content-Language: en-US, nl From: Hans de Goede In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi, On 31-Mar-25 1:46 PM, Rafael J. Wysocki wrote: > On Fri, Mar 28, 2025 at 10:09 PM Gergo Koteles 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@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 >> --- >> 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 Regards, Hans > >> drivers/acpi/acpi_video.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c >> index efdadc74e3f4..103f29661576 100644 >> --- a/drivers/acpi/acpi_video.c >> +++ b/drivers/acpi/acpi_video.c >> @@ -649,6 +649,13 @@ acpi_video_device_EDID(struct acpi_video_device *device, void **edid, int length >> >> 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; >> @@ -658,7 +665,7 @@ acpi_video_device_EDID(struct acpi_video_device *device, void **edid, int length >> ret = -EFAULT; >> } >> >> - kfree(obj); >> + kfree(buffer.pointer); >> return ret; >> } >> >> -- >> 2.49.0 >> >