Ticket #1411 (closed enhancement: wontfix)
Video compression buffers may be needed.
| Reported by: | jg | Owned by: | rsmith |
|---|---|---|---|
| Priority: | high | Milestone: | Trial-3 |
| Component: | distro | Version: | |
| Keywords: | power | Cc: | JordanCrouse, jg |
| Action Needed: | Verified: | no | |
| Deployments affected: | Blocked By: | ||
| Blocking: |
Description (last modified by jg) (diff)
The Geode has video compression buffers that can greatly reduce the memory bandwidth required to drive the display, but since we haven't seen any problems with bandwidth starvation on the mbus yet,it might be a non starter.
Leaving it off saves us oodles of video space, and we just recently discovered that EXA doesn't like having its stride pulled out from underneath it, meaning that we would probably have to have the compression pitch enabled for the non-visible space too, which would be a total waste.
On the other hand, memory references to the RAM chips take power, so the compression buffers may be needed to reduce power consumption when driving the display. But the idle display may be able to be handled by the DCON, (if we can tolerate the latency effects, which are not great if the video drivers are left on in the Geode), so this is not an obvious decision at all.
The compression buffers have been working in the past; but we need to make real measurements to decide the cost/benefit ratio of using them.
It is something we need to investigate carefully as part of the power management work.
