[PATCH v2] drm/edid/firmware: Remove built-in EDIDs
Pekka Paalanen
pekka.paalanen at haloniitty.fi
Wed Feb 21 11:07:31 UTC 2024
On Wed, 21 Feb 2024 10:26:36 +0100
Maxime Ripard <mripard at kernel.org> wrote:
> The EDID firmware loading mechanism introduced a few built-in EDIDs that
> could be forced on any connector, bypassing the EDIDs it exposes.
>
> While convenient, this limited set of EDIDs doesn't take into account
> the connector type, and we can end up with an EDID that is completely
> invalid for a given connector.
>
> For example, the edid/800x600.bin file matches the following EDID:
...
>
> So, an analog monitor EDID. However, if the connector was an HDMI
> monitor for example, it breaks the HDMI specification that requires,
> among other things, a digital display, the VIC 1 mode and an HDMI Forum
> Vendor Specific Data Block in an CTA-861 extension.
>
> We thus end up with a completely invalid EDID, which thus might confuse
> HDMI-related code that could parse it.
>
> After some discussions on IRC, we identified mainly two ways to fix
> this:
>
> - We can either create more EDIDs for each connector type to provide
> a built-in EDID that matches the resolution passed in the name, and
> still be a sensible EDID for that connector type;
>
> - Or we can just prevent the EDID to be exposed to userspace if it's
> built-in.
>
> Or possibly both.
>
> However, the conclusion was that maybe we just don't need the built-in
> EDIDs at all and we should just get rid of them. So here we are.
Sounds good to me.
Acked-by: Pekka Paalanen <pekka.paalanen at collabora.com>
If it turns out that these cannot be completely removed, then yet
another option would to refuse to use these on digital connectors.
Thanks,
pq
>
> Acked-by: Thomas Zimmermann <tzimmermann at suse.de>
> Signed-off-by: Maxime Ripard <mripard at kernel.org>
> ---
> Documentation/admin-guide/edid.rst | 35 +--
> .../admin-guide/kernel-parameters.txt | 14 +-
> drivers/gpu/drm/drm_edid_load.c | 160 +---------
> tools/edid/1024x768.S | 43 ---
> tools/edid/1280x1024.S | 43 ---
> tools/edid/1600x1200.S | 43 ---
> tools/edid/1680x1050.S | 43 ---
> tools/edid/1920x1080.S | 43 ---
> tools/edid/800x600.S | 40 ---
> tools/edid/Makefile | 37 ---
> tools/edid/edid.S | 274 ------------------
> tools/edid/hex | 1 -
> 12 files changed, 18 insertions(+), 758 deletions(-)
> delete mode 100644 tools/edid/1024x768.S
> delete mode 100644 tools/edid/1280x1024.S
> delete mode 100644 tools/edid/1600x1200.S
> delete mode 100644 tools/edid/1680x1050.S
> delete mode 100644 tools/edid/1920x1080.S
> delete mode 100644 tools/edid/800x600.S
> delete mode 100644 tools/edid/Makefile
> delete mode 100644 tools/edid/edid.S
> delete mode 100644 tools/edid/hex
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