Hi Linus, On Tue, Jan 5, 2021 at 11:23 PM Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > > On Mon, Dec 21, 2020 at 4:28 PM Martin Blumenstingl > <martin.blumenstingl@xxxxxxxxxxxxxx> wrote: > > On Wed, Oct 7, 2020 at 9:44 PM Martin Blumenstingl > > <martin.blumenstingl@xxxxxxxxxxxxxx> wrote: > > [...] > > > > As noted on the earlier patches I think this should be folded into the > > > > existing XHCI USB driver in drivers/usb/host/xhci-pci.c or, if that > > > > gets messy, as a separate bolt-on, something like > > > > xhci-pci-gpio.[c|h] in the drivers/usb/host/* directory. > > > > You can use a Kconfig symbol for the GPIO portions or not. > > > OK, I will do that if there are no objections from other developers > > > I am intending to place the relevant code in xhci-pci-etron.c, similar > > > to what we already have with xhci-pci-renesas.c > > > > I tried this and unfortunately there's a catch. > > the nice thing about having a separate GPIO driver means that the > > xhci-pci driver doesn't need to know about it. > > Since PCI devices have device-wide power management and things > like that I think that is a really dangerous idea. > > What if the GPIO driver starts poking around in this PCI device > when the main driver is also probed and has put the device > into sleep state? that is asking for trouble, indeed. [...] > > I implemented xhci-pci-etron.c and gave it a Kconfig option. > > xhci-pci is then calling into xhci-pci-etron (through some > > etron_xhci_pci_probe function). > > This sounds about right. > > > unfortunately this means that xhci-pci now depends on xhci-pci-etron. > > for xhci-pci-renesas this is fine (I think) because that part of the > > code is needed to get the xHCI controller going > > but for xhci-pci-etron this is a different story: the GPIO controller > > is entirely optional and only used on few devices > > I might be naive but should it not be the other way around? > That xhci-pci-etron is dependent on xhci-pci? I imagine > it would be an optional add-on. the only way to achieve this that I can think of is to basically have xhci-pci-etron implement it's own pci_driver and then call xhci_pci_probe, xhci_pci_remove, etc. but then it depends on the driver load order if the GPIO controller is exposed what structure did you have in mind to achieve this? > > my goal is (at some point in the future) to have the GPIO driver in OpenWrt. > > I am not sure if they would accept a patch where xhci-pci would then > > pull in the dependencies for that Etron controller, even though most > > boards don't need it. > > Make sure the etron part is an additional module that can be > loaded after xhci-pci. my approach from above unfortunately would not achieve this so if you have an idea how to achieve this (or have any other driver in mind that I can use as reference, even if not related to GPIO/USB/PCI then please let me know) > OpenWrt support optional modules to be compiled per-system. that I already found out. That's why I think that I need to get the driver part "right" and then get the OpenWrt part done in just a few lines of their build-system Best regards, Martin
