Radeon Power Management Gets More Fixes For 3.11

Just days after the first release candidate of the Linux 3.11 kernel, additional user testing of the new Radeon dynamic power management support has revealed more bugs in the open-source driver. Fortunately, there's already another pull request for Linux 3.11 to take care of some more Radeon "DPM" issues.

Alex Deucher sent in a pull request (actually, two) today for better fixing up the Radeon dynamic power management support. There's already been multiple pull requests to address DPM fallout, but this latest round of issues resolved include:

- The radeon.aspm=0 kernel module parameter has been introduced for disabling ASPM support. PCI Express Active-State Power Management (PCI-E ASPM) was added for the open Radeon driver as part of the DPM changes, but for certain motherboards it will lead to hangs. For those that remember the ASPM power issues Phoronix uncovered in years prior, this shouldn't be a big surprise, but now if you're hitting hangs there is this workaround.

- An endian bug was corrected in the Atom table parsing code.

- There's a fix for the Atom-based vRAM table parsing to take care of some problems with certain Radeon GPUs when switching the memory clock speeds.

- Workarounds for GCC compiler bugs in the Radeon DPM Atom code.

- Debugfs support to read the RS780/RS880 dynamic power management information, similar to the other debugfs entries added for different Radeon GPUs.

For those that didn't see yesterday's article, depending upon the AMD Radeon hardware, DPM can really drive up the open-source Radeon graphics performance. For those not yet experimenting with the feature on the yet-to-be-released Linux 3.11 kernel, more tests are forthcoming for this code on Phoronix.