On Fri, Aug 05, 2016 at 11:04:21AM +0200, Enrico Weigelt, metux IT consult wrote:
On 05.08.2016 10:15, Daniel Vetter wrote:
Hi,
There's a driver cap DRM_CAP_DUMB_PREFER_SHADOW for this. If set, render into a shadow buffer and copy over in bursts, otherwise you can assume that the memory is fully cpu cached and fast with random access.
aaaah!
nekrad@orion:~/src/linux$ git grep prefer_shadow drivers/gpu/drm/i915 drivers/gpu/drm/i915/intel_display.c: dev->mode_config.prefer_shadow = 1;
IOW: i915 driver (my notebook here has an i915) sets that flag, so it seems my guess is right.
Do we already have some suitable double-buffer helpers, which can detect changed regions and copy over in bursts, so userland doesn't need extra logic for that ? (hmm, maybe some cow + pagefault magic?)
... seems I need to give it some further thoughts ...
DIRTY_FB ioctl. But that's for other manual uplaod displays and similar things. -Daniel