The ACPI specification allows for an EDID to be up to 512 bytes but the _DDC EDID fetching code will only try up to 256 bytes.
Modify the code to instead start at 512 bytes and work it's way down instead. 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 Signed-off-by: Mario Limonciello <mario.limoncie...@amd.com> --- drivers/acpi/acpi_video.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c index 62f4364e4460..b3b15dd4755d 100644 --- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -624,6 +624,10 @@ acpi_video_device_EDID(struct acpi_video_device *device, arg0.integer.value = 1; else if (length == 256) arg0.integer.value = 2; + else if (length == 384) + arg0.integer.value = 3; + else if (length == 512) + arg0.integer.value = 4; else return -EINVAL; @@ -1443,7 +1447,7 @@ int acpi_video_get_edid(struct acpi_device *device, int type, int device_id, for (i = 0; i < video->attached_count; i++) { video_device = video->attached_array[i].bind_info; - length = 256; + length = 512; if (!video_device) continue; @@ -1478,13 +1482,18 @@ int acpi_video_get_edid(struct acpi_device *device, int type, int device_id, if (ACPI_FAILURE(status) || !buffer || buffer->type != ACPI_TYPE_BUFFER) { - length = 128; - status = acpi_video_device_EDID(video_device, &buffer, - length); - if (ACPI_FAILURE(status) || !buffer || - buffer->type != ACPI_TYPE_BUFFER) { - continue; + while (length) { + length -= 128; + status = acpi_video_device_EDID(video_device, &buffer, + length); + if (ACPI_FAILURE(status) || !buffer || + buffer->type != ACPI_TYPE_BUFFER) { + continue; + } + break; } + if (!length) + continue; } *edid = buffer->buffer.pointer; -- 2.34.1
