Messages in this thread |  | | Date | Fri, 10 Apr 2026 01:09:00 +0300 | | From | Dmitry Baryshkov <> | | Subject | Re: [PATCH v12 05/25] drm/atomic-helper: Add HDMI bridge output bus formats helper |
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On Thu, Apr 09, 2026 at 05:44:55PM +0200, Nicolas Frattaroli wrote: > The drm_bridge_funcs atomic_get_output_bus_fmts operation should be the > same for likely every HDMI connector bridge, unless such an HDMI > connector bridge has some special hardware restrictions that I cannot > envision yet. > > To avoid code duplication and standardize on a set of media bus formats > that the HDMI output color formats translate to, add a common helper > function that implements this operation to the drm bridge helpers. > > The function returns a list of output bus formats based on the HDMI > bridge's current output bits-per-component, and its bitmask of supported > color formats. > > To guard against future expansion of DRM_OUTPUT_COLOR_FORMAT outgrowing > the hweight8 call, add a BUILD_BUG_ON statement where it's used that > checks for DRM_OUTPUT_COLOR_FORMAT_COUNT. The justification for not > using hweight32 in all cases is that not all ISAs have a popcount > instruction, and will benefit from a smaller/faster software > implementation that doesn't have to operate across all bits. > > The justification for not defining an hweight_color depending on the > value of DRM_OUTPUT_COLOR_FORMAT_COUNT is that this count enum value is > only known at compile time, not at preprocessor time. > > Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com> > --- > drivers/gpu/drm/drm_atomic_helper.c | 81 +++++++++++++++++++++++++++++++++++++ > include/drm/drm_atomic_helper.h | 7 ++++ > 2 files changed, 88 insertions(+) >
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
-- With best wishes Dmitry
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