On Tue, Aug 27, 2019 at 09:47:56PM +0800, Kai-Heng Feng wrote:
It's a common practice to let dGPU unbound and use PCI port PM to disable its power through _PR3. When the dGPU comes with an HDA function, the HDA won't be suspended if the dGPU is unbound, so the dGPU power can't be disabled.
Just a terminology question:
I thought "using PCI port PM" meant using the PCI Power Management Capability in config space to directly change the device's power state, e.g., in pci_raw_set_power_state().
And I thought using _PS3, _PR3, etc would be part of "platform power management"?
And AFAICT, _PR3 merely returns a list of power resources; it doesn't disable power itself.
Commit 37a3a98ef601 ("ALSA: hda - Enable runtime PM only for discrete GPU") only allows HDA to be runtime-suspended once GPU is bound, to keep APU's HDA working.
However, HDA on dGPU isn't that useful if dGPU is unbound. So let relax the runtime suspend requirement for dGPU's HDA function, to save lots of power.
BugLink: https://bugs.launchpad.net/bugs/1840835 Signed-off-by: Kai-Heng Feng kai.heng.feng@canonical.com
sound/pci/hda/hda_intel.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c index 99fc0917339b..d4ee070e1a29 100644 --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -1285,7 +1285,8 @@ static void init_vga_switcheroo(struct azx *chip) dev_info(chip->card->dev, "Handle vga_switcheroo audio client\n"); hda->use_vga_switcheroo = 1;
hda->need_eld_notify_link = 1; /* cleared in gpu_bound op */
/* cleared in gpu_bound op */hda->need_eld_notify_link = !pci_pr3_present(p);-- 2.17.1