[PATCH] dm: pinctrl: Revert "pinctrl: probe pinctrl drivers during post-bind"

[Simon Glass]

Hi,

On Tue, 3 Jan 2023 at 10:05, Simon Glass <sjg at chromium.org> wrote:
>
> Hi Robert,
>
> On Fri, 30 Dec 2022 at 13:26, Robert Marko <robert.marko at sartura.hr> wrote:
> >
> >
> >
> > On Fri, Dec 30, 2022 at 8:02 PM Simon Glass <sjg at chromium.org> wrote:
> >>
> >> Hi Pali,
> >>
> >> On Fri, 30 Dec 2022 at 12:02, Pali Rohár <pali at kernel.org> wrote:
> >> >
> >> > On Friday 30 December 2022 11:47:29 Simon Glass wrote:
> >> > > Hi Pali,
> >> > >
> >> > > On Fri, 30 Dec 2022 at 10:13, Pali Rohár <pali at kernel.org> wrote:
> >> > > >
> >> > > > On Friday 30 December 2022 10:00:11 Simon Glass wrote:
> >> > > > > Hi Pali,
> >> > > > >
> >> > > > > On Fri, 30 Dec 2022 at 09:53, Pali Rohár <pali at kernel.org> wrote:
> >> > > > > >
> >> > > > > > On Friday 30 December 2022 09:30:27 Simon Glass wrote:
> >> > > > > > > Hi Pali,
> >> > > > > > >
> >> > > > > > > On Wed, 21 Dec 2022 at 17:02, Pali Rohár <pali at kernel.org> wrote:
> >> > > > > > > >
> >> > > > > > > > On Wednesday 21 December 2022 07:27:39 Simon Glass wrote:
> >> > > > > > > > > This breaks chromebook_coral and it is also not how things should work. If
> >> > > > > > > > > a board needs to bind GPIOs as part of a pinctrl driver this can be done
> >> > > > > > > > > during the bind step, if needed.
> >> > > > > > > > >
> >> > > > > > > > > We cannot probe pinctrl devices when binding as a rule, since it cannot be
> >> > > > > > > > > supported on some platforms.
> >> > > > > > > > >
> >> > > > > > > > > The bind and probe steps are separate in U-Boot and they should remain
> >> > > > > > > > > separate.
> >> > > > > > > > >
> >> > > > > > > > > This reverts commit f9ec791b5e24378b71590877499f8683d5f54dac.
> >> > > > > > > >
> >> > > > > > > > Unfortunately reverting this patch would break other devices, mostly
> >> > > > > > > > A3720 based where pinctrl driver acts also as gpio driver. Because no
> >> > > > > > > > other caller then register gpio driver and so other drivers which parses
> >> > > > > > > > gpios from DT (which belongs to that gpio driver) will fail during
> >> > > > > > > > probe.
> >> > > > > > >
> >> > > > > > > That is something to be sorted out for that platform. You can bind
> >> > > > > > > GPIO devices in the pinctrl driver's bind() method as other SoCs do.
> >> > > > > > > Even better, the device tree typically has that info in it, i.e. GPIO
> >> > > > > > > subnodes within the pinctrl node.
> >> > > > > > >
> >> > > > > > > Probing pinctrl in a bind function is unfortunately just wrong. It
> >> > > > > > > will cause all sorts of problems, and perhaps already has.
> >> > > > > >
> >> > > > > > Ok, so it means that drivers/pinctrl/mvebu/pinctrl-armada-37xx.c needs
> >> > > > > > to be refactored and fixed to handle these restrictions.
> >> > > > >
> >> > > > > It is not a restriction. It is simply that binding and probing are
> >> > > > > different things and we should not tie them together. It will just
> >> > > > > become a nightmare for board bringup and other drivers.
> >> > > > >
> >> > > > > >
> >> > > > > > > > Also I think that pinctrl command would not work in this case if pinctrl
> >> > > > > > > > would not be probed.
> >> > > > > > >
> >> > > > > > > Devices are probed before use, including by commands.
> >> > > > > > >
> >> > > > > > > This is quite important to fix before the release.
> >> > > > > >
> >> > > > > > Unfortunately in this time I do not have any a3720 board for testing.
> >> > > > > > Robert was able to easily trigger this issue and also introduced that
> >> > > > > > commit f9ec791b5e24 ("pinctrl: probe pinctrl drivers during post-bind").
> >> > > > > >
> >> > > > > > So may I ask Robert to look at it? In past days I looked at powerpc
> >> > > > > > release issues and I do not have time for other things.
> >> > > > >
> >> > > > > That driver has a few FIXMEs in it and could use a look anyway. I see
> >> > > > > that the gpio controller is a subnode of pinctrl anyway. Adding a
> >> > > > > compatible string for it would fix the problem  just like that, and
> >> > > > > remove a lot of ugly code in the driver. This Linux-centric nature of
> >> > > > > device tree bindings really is infuriating:
> >> > > >
> >> > > > All a3720 DTS files are 1:1 copied from Linux. So if problem is in DTS
> >> > > > file then it should be discussed with Linux dt/mvebu maintainers. This
> >> > > > year I fixed U-Boot code to handle Linux a3720 DTS files and then copied
> >> > > > DTS files from Linux. So it is not a good idea to have again different
> >> > > > DTS file for u-boot and different for kernel.
> >>
> >> That was not my suggestion. I would simply like the bindings in Linux
> >> to be more explicit, rather than having driver code manually written
> >> to do what the device tree is supposed to do.
> >>
> >> > > >
> >> > > > > /* FIXME: Use livtree and check the result of device_bind() below */
> >> > > > > fdt_for_each_subnode(subnode, blob, node) {
> >> > > > >     if (fdtdec_get_bool(blob, subnode, "gpio-controller")) {
> >> > > > >         ret = 0;
> >> > > > >         break;
> >> > > > >     }
> >> > > > > };
> >> > > > > if (ret)
> >> > > > >    return ret;
> >> > > > >
> >> > > > >
> >> > > > > Failing that it just needs a bind() method that calls
> >> > > > > armada_37xx_gpiochip_register()
> >> > > > >
> >> > > > > Regards,
> >> > > > > Simon
> >> > > >
> >> > > > Seems that it is not such simple. armada_37xx_gpiochip_register()
> >> > > > depends on initialized and bound pinctrl part of driver. So before
> >> > > > binding gpio you need to bind pinctrl as they share internal structures.
> >> > >
> >> > > Where are you seeing that? From what I can tell it just binds the GPIO
> >> > > driver. It doesn't probe it. So long as you bind the GPIO driver in
> >> > > armada_37xx_pinctrl_bind() it should be equivalent.
> >> >
> >> > armada_37xx_gpiochip_register() calls device_bind() for
> >> > &armada_37xx_gpio_driver which probe method armada_37xx_gpio_probe() and
> >> > ops &armada_37xx_gpio_ops callbacks access a37xx pinctrl internal
> >> > structures.
> >>
> >> Yes but probing is different from binding, please see [1]
> >>
> >> >
> >> > So I'm not sure if there is an issue or not. But for sure a37xx gpio
> >> > must be probed after a37xx pinctrl is probed because a37xx pinctrl probe
> >> > function fills internal a37xx pinctrl strucutre used by a37xx gpio probe
> >> > function.
> >>
> >> Yes, children are probed after parents, as in docs:
> >>
> >> "All parent devices are probed. It is not possible to activate a
> >> device unless its predecessors (all the way up to the root device) are
> >> activated. This means (for example) that an I2C driver will require
> >> that its bus be activated."
> >
> >
> > Hi Simon,
> > Finally, catching up with emails.
> >
> > The issue here is that there is nothing probing the pinctrl driver as no pinmuxing on that
> > controller is being done and so GPIO doesn't get probed as well which in turn is breaking
> > networking as Methode eDPU board only has SFP ports and TX disable remains active since
> > the networking driver cannot toggle the GPIO as it's not registered.
> >
> > Other than inventing a pinmux node and attaching it so that controller gets probed I dont see
> > how to solve it within the current U-boot scope.
>
> Did you see my comments above? You only need to change it to do things
> in the pinctrl bind() method, instead of the probe() method. It should
> be pretty easy...let me know if you get stuck.
>

Applied to u-boot/dm

Please can you look at this before the next release?

Regards,
Simon