Intel Linux Driver Wiring Up New "vRAM Self Refresh" Feature For Arc Graphics Cards
With the upcoming Linux 5.19 cycle appearing to be the point at which Intel's DG2/Alchemist Linux graphics driver support is settling down and may end up being the base version requirement for their forthcoming discrete graphics cards, we are seeing other non-core feature work happen for these Arc Graphics products. A new feature we've only seen mentioned today for the first time by Intel is "vRAM SR", short for vRAM Self-Refresh.
The vRAM Self-Refresh support is debuting with upcoming Intel discrete graphics cards for use during D3cold and S0ix system-wide suspend. vRAM Self-Refresh avoids having to possibly evict local memory objects over to system memory during the low-power states. The vRAM Self-Refresh is able to retain the dedicated video memory context and allowing it to be restored when exiting the D3cold power state. In turn this feature lowers the latency when leaving the low-power state but does come at a slight power consumption cost with retaining the dedicated video memory state by keeping it partially powered-up.
The Intel Arc Graphics client graphics cards also alternatively support the "D3Cold-Off" mode instead of "D3Cold-VRSR" where there is the maximum power savings (zero Watt) albeit with the higher exit latency.
This Intel vRAM Self-Refresh functionality also depends upon support from the host BIOS for functioning. The vRAM Self-Refresh support also is supported by the earlier DG1 development graphics cards but the Linux driver has not supported it to this point, though that could change once the DG2 support is squared away.
This Intel vRAM SR work follows other DG2 power management work seen as well in recent days for getting Intel's client graphics cards ready to run well on Linux.
See this patch series for more details. Though due to the timing of this series it's not expected to land now until the 5.20~6.0 kernel cycle.
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