[+cc Peter, Mika, Dave] https://lore.kernel.org/r/20190827134756.10807-1-kai.heng.feng@xxxxxxxxxxxxx On Wed, Aug 28, 2019 at 12:58:28AM +0800, Kai-Heng Feng wrote: > at 23:25, Takashi Iwai <tiwai@xxxxxxx> wrote: > > On Tue, 27 Aug 2019 15:47:55 +0200, > > Kai-Heng Feng wrote: > > > A driver may want to know the existence of _PR3, to choose different > > > runtime suspend behavior. A user will be add in next patch. > > > > > > This is mostly the same as nouveau_pr3_present(). > > > > Then it'd be nice to clean up the nouveau part, too? > > nouveau_pr3_present() may call pci_d3cold_disable(), and my intention is to > only check the presence of _PR3 (i.e. a dGPU) without touching anything. It looks like Peter added that code with 279cf3f23870 ("drm/nouveau/acpi: use DSM if bridge does not support D3cold"). I don't understand the larger picture, but it is somewhat surprising that nouveau_pr3_present() *looks* like a simple predicate with no side-effects, but in fact it disables the use of D3cold in some cases. If the disable were moved to the caller, Kai-Heng's new interface could be used both places.
