Messages in this thread |  | | From | Nicolas Frattaroli <> | | Subject | Re: [PATCH v6 0/2] Add "link bpc" DRM property | | Date | Wed, 01 Apr 2026 14:17:41 +0200 |
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On Monday, 30 March 2026 10:33:08 Central European Summer Time Nicolas Frattaroli wrote: > This series adds a new "link bpc" DRM property. It reflects the display > link's actual achieved output bits per component, considering any > degradation of the bit depth done by drivers for bandwidth or other > reasons. The property's value is updated during an atomic commit, which > is also when it fires an uevent if it changed to let userspace know. > > There's a weston implementation at [1] which makes use of this new > property. It is not representative of the entire use case of the > property, but rather a proof-of-concept. > > [1]: https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/1850 > > --- > Changes in v6: > - Drop amdgpu patch to unblock series. > - Reword property documentation to make it more explicit as to what bits > this counts and why someone would want this. > - Reword first patch message to do the same. > - Link to v5: https://lore.kernel.org/r/20260319-link-bpc-v5-0-5306cd04a708@collabora.com > > Changes in v5: > - Split "drm/connector: hdmi: Add a 'link bpc' property" into two > patches; one adding the property, the other making use for it in the > HDMI helpers (Maxime) > - Apply Maxime's Ack to the two split patches as per the review > - Link to v4: https://lore.kernel.org/r/20260311-link-bpc-v4-0-51775e964720@collabora.com > > Changes in v4: > - Throw out the workqueue and delayed work item > - Remove the drm_connector_update_link_bpc_state function > - Reimplement it by updating the property and firing the uevent in > commit_tail > - Check that the provided max_bpc value in attach_link_bpc_property is > within the expected range > - Clamp the connector state's link_bpc value between 8 and max_bpc so > that no value outside the declared range is ever written to the drm > property > - Update and reword doc strings > - Add an amdgpu implementation > - Link to v3: https://lore.kernel.org/r/20251022162843.1759-1-marius.vlad@collabora.com/T/ > > Changes in v3: > - remove VRR mention from commit description (Ville) > - add DRM_MODE_PROP_IMMUTABLE to flags (Ville) > - provide helpers functions for drivers to use (can be used by other > types of connectors, not just HDMI) > - send uevent informating userspace when 'link bpc' connector state > changed (Daniel @ https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/1850) > - added missing doc entry > - Link to v2: https://lore.kernel.org/r/20251006083043.3115-1-marius.vlad@collabora.com/T/ > > Changes in v2: > - replace return with EBUSY if connector already exists (Dmitry) > - add i-g-t test and an implementation for Weston (Dmitry) > - re-wording patch description (Jani) > - Link to v1: https://lore.kernel.org/r/20250801101750.1726-1-marius.vlad@collabora.com/T/ > > Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com> > > --- > Nicolas Frattaroli (2): > drm/connector: Add a 'link bpc' property > drm/connector: hdmi: Add support for 'link bpc' property > > drivers/gpu/drm/display/drm_hdmi_state_helper.c | 2 + > drivers/gpu/drm/drm_atomic_helper.c | 9 +++ > drivers/gpu/drm/drm_atomic_uapi.c | 2 + > drivers/gpu/drm/drm_connector.c | 88 +++++++++++++++++++++++++ > include/drm/drm_connector.h | 16 +++++ > 5 files changed, 117 insertions(+) > --- > base-commit: 3a48a999a2e3c3d1988d44370ed8f43ff54700b6 > change-id: 20260309-link-bpc-d0afc475ac49 > > Best regards, > -- > Nicolas Frattaroli <nicolas.frattaroli@collabora.com> > >
There's a lot of unresolved discussion on v5 of the series going on at the moment, so please don't merge v6 despite the acks, there will likely be a v7.
Kind regards, Nicolas Frattaroli
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