https://bugs.freedesktop.org/show_bug.cgi?id=102468

Bug ID: 102468 Summary: RX470 powerplay issues on hybrid laptop system (dGPU does not power down) Product: DRI Version: unspecified Hardware: x86-64 (AMD64) OS: Linux (All) Status: NEW Severity: normal Priority: medium Component: DRM/AMDgpu Assignee: dri-devel@lists.freedesktop.org Reporter: taijian@posteo.de

Created attachment 133866 --> https://bugs.freedesktop.org/attachment.cgi?id=133866&action=edit relevant dmesg output

I have an Alienware 15R3 laptop with hybrid Intel (HD 630) / AMD (RX470) graphics. I run Arch Linux, up to date as of 2017-08-29.

My issue is that when booting the laptop with a 'normal' kernel command line, the dGPU *never* turns off, even when it is not normally needed in desktop operations. This is confirmed by running powertop, which reports a power drain of ~36 W even under basically zero load. This is accompanied by various [powerplay] error messages in dmesg. As a side effect, the CPU is blocked from going to power states below pc2.

If I blacklist amdgpu in the kcl and then force the dGPU to off with acpi_call, the reported power consumption in powertop drops to ~12 W, with a corresponding increase in battery time. The CPU is now able to reach pc3.

Booting into Windows 10 also gives me the same battery time as blacklisting amdgpu in Linux, but also the expected 'on-demand-switching' of the dGPU that I expect from such a setup. This is just to confirm that this is not a hardware issue - it is definitely possible to dynamically switch the dGPU on or off from the OS level, the implementation is just botched in amdgpu.