Hey Maarten, On Fri, Jun 29, 2018 at 12:05 PM, Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> wrote: > Op 22-02-18 om 04:54 schreef Stefan Schake: >> Android assumes an implicit black background layer is always present >> behind all layers it specifies for composition. drm_hwcomposer currently >> punts responsibility for this to the kernel/DRM platform and puts layers >> with per-pixel alpha content on the primary plane when requested. >> >> On some platforms (e.g. VC4) a background color fill has a cycle cost for >> the hardware composer and is not enabled by default. Instead, userland can >> request a background color through a CRTC property. Use this property to >> specify the implicit black background Android expects. >> >> Signed-off-by: Stefan Schake <stschake@xxxxxxxxx> >> --- >> Kernel changes for this (background_color) are available here: >> >> https://github.com/stschake/linux/commits/background-upstream >> >> Sending as RFC because I'm not entirely clear on whose responsibility >> this should be, on most DRM drivers it seems to be implicit. I think >> a case could also be made that VC4 should not accept alpha formats on >> the lowest layer or enable background color fill when given one anyway. >> On the other hand, userland control over background color seems desirable >> regardless and is a feature of multiple hardware composers (i915, vc4, omap). > Ping? Would be nice if we were moving forward. :) I was unclear if DRM specified a black background when writing this. Someone pointed me towards the excerpt in the docs that explicitly mandates black background fill and so I ended up writing a VC4 patch that automatically sets it when required instead of the optional property used here. Adding a background_color property would still be desirable, but I'm unclear on what the userspace would be at the moment. drm_hwc doesn't need any background color other than black and since that is the DRM default, it wouldn't need to use a property. Thanks, Stefan _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
