Re: [PATCH v1 1/1] gpiolib: Read "gpio-line-names" from a firmware node

[Marek Vasut]

On 4/10/21 11:06 AM, Bartosz Golaszewski wrote:
> On Sat, Apr 10, 2021 at 2:46 AM Marek Vasut <marex@xxxxxxx> wrote:
> > On 3/15/21 6:04 PM, Andy Shevchenko wrote:
> > > On Mon, Mar 15, 2021 at 6:49 PM Bartosz Golaszewski
> > > <bgolaszewski@xxxxxxxxxxxx> wrote:
> > > > On Mon, Mar 15, 2021 at 3:34 PM Andy Shevchenko
> > > > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > > > > On Mon, Mar 15, 2021 at 03:04:37PM +0100, Bartosz Golaszewski wrote:
> > > > > > On Mon, Mar 15, 2021 at 1:50 PM Andy Shevchenko
> > > > > > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > > > > > > On Mon, Mar 15, 2021 at 12:16:26PM +0200, Andy Shevchenko wrote:
> > > > > > > > On Mon, Mar 15, 2021 at 10:01:47AM +0100, Bartosz Golaszewski wrote:
> > > > > > > > > On Fri, Mar 5, 2021 at 1:03 PM Andy Shevchenko
> > > > > > > > > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > > > > > > >
> > > > > > > > > Unfortunately while this may fix the particular use-case on STM32, it
> > > > > > > > > breaks all other users as the 'gpio-line-names' property doesn't live
> > > > > > > > > on dev_fwnode(&gdev->dev) but on dev_fwnode(chip->parent).
> > > > > > > > >
> > > > > > > > > How about we first look for this property on the latter and only if
> > > > > > > > > it's not present descend down to the former fwnode?
> > > > > > > >
> > > > > > > > Oops, I have tested on x86 and it worked the same way.
> > > > > > > >
> > > > > > > > Lemme check this, but I think the issue rather in ordering when we apply fwnode
> > > > > > > > to the newly created device and when we actually retrieve gpio-line-names
> > > > > > > > property.
> > > > > > >
> > > > > > > Hmm... I can't see how it's possible can be. Can you provide a platform name
> > > > > > > and pointers to the DTS that has been broken by the change?
> > > > > >
> > > > > > I noticed it with gpio-mockup (libgpiod tests failed on v5.12-rc3) and
> > > > > > the WiP gpio-sim - but it's the same on most DT platforms. The node
> > > > > > that contains the `gpio-line-names` is the one associated with the
> > > > > > platform device passed to the GPIO driver. The gpiolib then creates
> > > > > > another struct device that becomes the child of that node but it
> > > > > > doesn't copy the parent's properties to it (nor should it).
> > > > > >
> > > > > > Every driver that reads device properties does it from the parent
> > > > > > device, not the one in gdev - whether it uses of_, fwnode_ or generic
> > > > > > device_ properties.
> > > > >
> > > > > What you are telling contradicts with the idea of copying parent's fwnode
> > > > > (or OF node) in the current code.
> > > >
> > > > Ha! While the OF node of the parent device is indeed assigned to the
> > > > gdev's dev, the same isn't done in the core code for fwnodes and
> > > > simulated chips don't have an associated OF node, so this is the
> > > > culprit I suppose.
> > >
> > > Close, but not fully correct.
> > > First of all it depends on the OF / ACPI / platform enumeration.
> > > Second, we are talking about secondary fwnode in the case where it happens.
> > >
> > > I'm in the middle of debugging this, I'll come up with something soon I believe.
> >
> > Was there ever any follow up on this ?
> >
> > I would like to point out that on STM32MP1 in Linux 5.10.y, the
> > gpio-line-names are still broken, and a revert of "gpiolib: generalize
> > devprop_gpiochip_set_names() for device properties" is still necessary.
>
> Yes, Andy has fixed that in commit b41ba2ec54a7 ("gpiolib: Read
> "gpio-line-names" from a firmware node") but for some reason this has
> never made its way into stable. I'll resend it.

Yes, that's the missing one, thanks. With that picked, the mp1 is fine.