On Mon, Jan 8, 2024 at 4:24 PM Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote: > > Hi, > > On 04/01/2024 14:01, Bartosz Golaszewski wrote: > > From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx> > > > > During last year's Linux Plumbers we had several discussions centered > > around the need to power-on PCI devices before they can be detected on > > the bus. > > > > The consensus during the conference was that we need to introduce a > > class of "PCI slot drivers" that would handle the power-sequencing. > > > > After some additional brain-storming with Manivannan and the realization > > that the DT maintainers won't like adding any "fake" nodes not > > representing actual devices, we decided to reuse the existing > > infrastructure provided by the PCIe port drivers. > > > > The general idea is to instantiate platform devices for child nodes of > > the PCIe port DT node. For those nodes for which a power-sequencing > > driver exists, we bind it and let it probe. The driver then triggers a > > rescan of the PCI bus with the aim of detecting the now powered-on > > device. The device will consume the same DT node as the platform, > > power-sequencing device. We use device links to make the latter become > > the parent of the former. > > > > The main advantage of this approach is not modifying the existing DT in > > any way and especially not adding any "fake" platform devices. > > I've successfully tested this serie for the WCN7850 Wifi/BT combo onboard chip > present on the SM8550-QRD and SM8650-QRD boards and it works just fine. > > Here's a branch with the wcn7850 vreg table added to the pwrseq driver, > and the DT changes: > https://git.codelinaro.org/neil.armstrong/linux/-/commits/topic/sm8x50/wcn7850-wifi-pwrseq/?ref_type=heads Thanks, I'll integrate them into v2. Bart
