On Thu, Oct 22, 2020 at 10:34:44AM +0000, Simon Ser wrote:

User-space should avoid parsing EDIDs for metadata already exposed via other KMS interfaces and properties. For instance, user-space should not try to extract a list of modes from the EDID: the kernel might mutate the mode list (because of link capabilities or quirks for instance).

Other metadata not exposed by KMS can be parsed by user-space. This includes for instance monitor identification (make/model/serial) and supported color-spaces.

v2: add short explanation why user-space shouldn't do this (Brian)

LGTM, thanks.

-Brian

Signed-off-by: Simon Ser contact@emersion.fr Suggested-by: Daniel Vetter daniel.vetter@intel.com Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Acked-by: Thomas Zimmermann tzimmermann@suse.de Cc: Pekka Paalanen pekka.paalanen@collabora.co.uk Cc: Ville Syrj�l� ville.syrjala@linux.intel.com Cc: Brian Starkey brian.starkey@arm.com

---

drivers/gpu/drm/drm_connector.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index 717c4e7271b0..1913d8b4e16a 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -960,6 +960,11 @@ static const struct drm_prop_enum_list dp_colorspaces[] = {

• drm_connector_update_edid_property(), usually after having parsed
• the EDID using drm_add_edid_modes(). Userspace cannot change this
• property.

• • User-space should not parse the EDID to obtain information exposed via
• • other KMS properties (because the kernel might apply limits, quirks or
• • fixups to the EDID). For instance, user-space should not try to parse
• • mode lists from the EDID.
  • DPMS:
  • Legacy property for setting the power state of the connector. For atomic
  • drivers this is only provided for backwards compatibility with existing

-- 2.28.0