From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Mario Limonciello <mario.limonciello@amd.com>
Cc: amd-gfx@lists.freedesktop.org,
Alex Deucher <alexander.deucher@amd.com>,
Harry Wentland <harry.wentland@amd.com>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Hans de Goede <hdegoede@redhat.com>,
"open list:ACPI" <linux-acpi@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
"open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
Melissa Wen <mwen@igalia.com>,
Mark Pearson <mpearson-lenovo@squebb.ca>
Subject: Re: [PATCH v3 1/5] ACPI: video: Handle fetching EDID that is longer than 256 bytes
Date: Fri, 2 Feb 2024 17:07:41 +0100 [thread overview]
Message-ID: <CAJZ5v0iw3PLB4W0QNmRCgK2AWxe5A7wxnWSz-Jm--Mb=fnugEw@mail.gmail.com> (raw)
In-Reply-To: <20240201221119.42564-2-mario.limonciello@amd.com>
On Thu, Feb 1, 2024 at 11:11 PM Mario Limonciello
<mario.limonciello@amd.com> 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@amd.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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
>
next prev parent reply other threads:[~2024-02-02 16:07 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-01 22:11 [PATCH v3 0/5] Add support for fetching EDID from ACPI _DDC Mario Limonciello
2024-02-01 22:11 ` [PATCH v3 1/5] ACPI: video: Handle fetching EDID that is longer than 256 bytes Mario Limonciello
2024-02-02 16:07 ` Rafael J. Wysocki [this message]
2024-02-02 16:09 ` Mario Limonciello
2024-02-06 19:43 ` Rafael J. Wysocki
2024-02-01 22:11 ` [PATCH v3 2/5] drm: Add drm_get_acpi_edid() helper Mario Limonciello
2024-02-02 10:24 ` Pranjal Ramajor Asha Kanojiya
2024-02-02 10:29 ` Jani Nikula
2024-02-02 15:19 ` Mario Limonciello
2024-02-01 22:11 ` [PATCH v3 3/5] drm/amd: Fetch the EDID from _DDC if available for eDP Mario Limonciello
2024-02-03 12:53 ` kernel test robot
2024-02-01 22:11 ` [PATCH v3 4/5] drm/nouveau: Use drm_get_acpi_edid() helper Mario Limonciello
2024-02-01 22:11 ` [PATCH v3 5/5] drm: Drop unneeded selects in DRM drivers Mario Limonciello
2024-02-02 10:12 ` Pranjal Ramajor Asha Kanojiya
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