Bug 16038
| Summary: | vga_switcheroo: kernel hang after OFF/ON after resume from pm-suspend | ||
|---|---|---|---|
| Product: | Drivers | Reporter: | Stefan Huber (shuber2) |
| Component: | Video(Other) | Assignee: | drivers_video-other |
| Status: | RESOLVED DUPLICATE | ||
| Severity: | normal | ||
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 2.6.34 | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
The following procedure leads to a hang of the kernel: 1. echo "OFF" > /sys/kernel/debug/vgaswitcheroo/switch to switch off the discrete adapter. 2. pm-suspend 3. resuming... 4. Power consumption indicates that both cards are powered but cat /sys/kernel/debug/vgaswitcheroo/switch claims that only the internal adapter is powered. As expected, calling echo "OFF" > /sys/kernel/debug/vgaswitcheroo/switch does not turn off the unused card. Anyhow, calling echo "ON" > /sys/kernel/debug/vgaswitcheroo/switch leads to a kernel hang. No output to the console, hence no back trace is available here. However, if one suspends the notebook with both cards powered, it works well. That means, that one can turn off the discrete adapter after resuming without problems. The system here is a Lenovo T400 with an Intel GMA X4500HD and a ATI Mobility Radeon HD 3470. Kernel version: gentoo-sources-2.6.34