| Message ID | V_APW3gKRhljvcmT28tGV3JkP7qW9Z7h45I-s2wiJvYhaaveCpYpg3tztZPsZVV2KV1NC7rUx08IUUgCJXzdRrWCsEGB0czq4ZozpdyVFLs=@emersion.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm: document that user-space should avoid parsing EDIDs | expand |
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 > >
On Thu, 22 Oct 2020 10:34:44 +0000 Simon Ser <contact@emersion.fr> 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) > > 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 Syrjälä <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 Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.com> Thanks, pq
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