Arch Linux

Description:
With mesa 13.0.0rc2 I'm seeing a 2 to 3 second delay when starting firefox, thunderbird or chromium. This happens every time the programs are closed (all instances) and run again. Glxgears (without prime offloading) also seems to be affected as well as lspci, this wasn't the case before with mesa 12.0.3.

When this happens the following messages are logged in dmesg:

[drm] probing gen 2 caps for device 8086:9d18 = 9724043/e
[drm] enabling PCIE gen 3 link speeds, disable with radeon.pcie_gen2=0
[drm] PCIE GART of 2048M enabled (table at 0x00000000001D6000).
radeon 0000:03:00.0: WB enabled
radeon 0000:03:00.0: fence driver on ring 0 use gpu addr 0x0000000080000c00 and cpu addr 0xffff88042bbafc00
radeon 0000:03:00.0: fence driver on ring 1 use gpu addr 0x0000000080000c04 and cpu addr 0xffff88042bbafc04
radeon 0000:03:00.0: fence driver on ring 2 use gpu addr 0x0000000080000c08 and cpu addr 0xffff88042bbafc08
radeon 0000:03:00.0: fence driver on ring 3 use gpu addr 0x0000000080000c0c and cpu addr 0xffff88042bbafc0c
radeon 0000:03:00.0: fence driver on ring 4 use gpu addr 0x0000000080000c10 and cpu addr 0xffff88042bbafc10
radeon 0000:03:00.0: fence driver on ring 5 use gpu addr 0x0000000000075a18 and cpu addr 0xffffc90002235a18
radeon 0000:03:00.0: failed VCE resume (-110).
[drm] ring test on 0 succeeded in 1 usecs
[drm] ring test on 1 succeeded in 1 usecs
[drm] ring test on 2 succeeded in 1 usecs
[drm] ring test on 3 succeeded in 4 usecs
[drm] ring test on 4 succeeded in 4 usecs
[drm] ring test on 5 succeeded in 2 usecs
[drm] UVD initialized successfully.
[drm] ib test on ring 0 succeeded in 0 usecs
[drm] ib test on ring 1 succeeded in 0 usecs
[drm] ib test on ring 2 succeeded in 0 usecs
[drm] ib test on ring 3 succeeded in 0 usecs
[drm] ib test on ring 4 succeeded in 0 usecs
[drm] ib test on ring 5 succeeded

I'm using a laptop with an Intel iGPU with and an AMD dGPU, it seems that with mesa 13.0.0rc2 all the gpus in the system (iGPU+dGPU) are probed instead of only the gpu that is going to be used (iGPU).

Given that the dGPU is usually automatically turned off for power saving it takes 2 to 3 seconds to be re-initialized and this causes the delay on startup for the programs I've mentioned before (I suspect many more are affected)

This might not be an actual bug (new intended behavior? Upstream should decide on that) but it is a change in behavior and it is annoying as running any affected application will incur a 2 to 3 second delay on startup, even if all files are already cached in ram and the startup would otherwise be virtually instant.


Additional info:
mesa 13.0.0rc2-2
Upstream bug report: https://bugs.freedesktop.org/show_bug.cgi?id=98502
Machine: Lenovo E560, iGPU Intel HD Graphics 520 (rev 07), dGPU [AMD/ATI] Mars [Radeon HD 8670A/8670M/8750M] (rev 81)

Steps to reproduce:
Close all instances of firefox and/or chromium, downgrade to mesa 12.0.3-3, start any of the affected programs, close it and run it again.
Update system and mesa to 13.0.0rc2, close and run affected programs.

Closing and running the affected programs makes sure they are cached in ram and HD speed will have less influence on the result.