On Thu, Feb 1, 2024 at 11:11 PM Mario Limonciello <mario.limonciello@xxxxxxx> wrote: > > 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. > > As _DDC is now called up to 4 times on a machine debugging messages > are noisier than necessary. Decrease from info to debug. > > 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.limonciello@xxxxxxx> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> or I can apply it if that's preferred. Thanks! > --- > v1->v2: > * Use for loop for acpi_video_get_edid() > * Use one of Rafael's suggestions for acpi_video_device_EDID() > * Decrease message level too > --- > drivers/acpi/acpi_video.c | 25 +++++++++---------------- > 1 file changed, 9 insertions(+), 16 deletions(-) > > diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c > index 4afdda9db019..3bfd013e09d2 100644 > --- a/drivers/acpi/acpi_video.c > +++ b/drivers/acpi/acpi_video.c > @@ -625,12 +625,9 @@ acpi_video_device_EDID(struct acpi_video_device *device, > > if (!device) > return -ENODEV; > - if (length == 128) > - arg0.integer.value = 1; > - else if (length == 256) > - arg0.integer.value = 2; > - else > + if (!length || (length % 128)) > return -EINVAL; > + arg0.integer.value = length / 128; > > status = acpi_evaluate_object(device->dev->handle, "_DDC", &args, &buffer); > if (ACPI_FAILURE(status)) > @@ -641,7 +638,8 @@ acpi_video_device_EDID(struct acpi_video_device *device, > if (obj && obj->type == ACPI_TYPE_BUFFER) > *edid = obj; > else { > - acpi_handle_info(device->dev->handle, "Invalid _DDC data\n"); > + acpi_handle_debug(device->dev->handle, > + "Invalid _DDC data for length %ld\n", length); > status = -EFAULT; > kfree(obj); > } > @@ -1447,7 +1445,6 @@ 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; > > if (!video_device) > continue; > @@ -1478,18 +1475,14 @@ int acpi_video_get_edid(struct acpi_device *device, int type, int device_id, > continue; > } > > - status = acpi_video_device_EDID(video_device, &buffer, length); > - > - if (ACPI_FAILURE(status) || !buffer || > - buffer->type != ACPI_TYPE_BUFFER) { > - length = 128; > + for (length = 512; length > 0; length -= 128) { > status = acpi_video_device_EDID(video_device, &buffer, > length); > - if (ACPI_FAILURE(status) || !buffer || > - buffer->type != ACPI_TYPE_BUFFER) { > - continue; > - } > + if (ACPI_SUCCESS(status)) > + break; > } > + if (!length) > + continue; > > *edid = buffer->buffer.pointer; > return length; > -- > 2.34.1 >
