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    SubjectRe: [PATCH v2] gpio: mt7621: support gpio-line-names property
    Hi Andy,

    On Fri, Jul 2, 2021 at 11:27 AM Andy Shevchenko
    <andy.shevchenko@gmail.com> wrote:
    >
    > On Sun, Jun 27, 2021 at 4:13 PM Sergio Paracuellos
    > <sergio.paracuellos@gmail.com> wrote:
    > > On Sun, Jun 27, 2021 at 3:01 PM Andy Shevchenko
    > > <andy.shevchenko@gmail.com> wrote:
    > > > On Sun, Jun 27, 2021 at 1:56 PM Sergio Paracuellos
    > > > <sergio.paracuellos@gmail.com> wrote:
    > > > > On Sun, Jun 27, 2021 at 12:51 PM Andy Shevchenko
    > > > > <andy.shevchenko@gmail.com> wrote:
    > > > > > On Sun, Jun 27, 2021 at 12:47 PM Sergio Paracuellos
    > > > > > <sergio.paracuellos@gmail.com> wrote:
    > > > > > > On Sun, Jun 27, 2021 at 11:33 AM Andy Shevchenko
    > > > > > > <andy.shevchenko@gmail.com> wrote:
    > > > > > > > On Sat, Jun 26, 2021 at 7:18 PM Sergio Paracuellos
    > > > > > > > <sergio.paracuellos@gmail.com> wrote:
    > > > > > > > >
    > > > > > > > > The default handling of the gpio-line-names property by the
    > > > > > > > > gpiolib-of implementation does not work with the multiple
    > > > > > > > > gpiochip banks per device structure used by the gpio-mt7621
    > > > > > > > > driver.
    > > > > > > > >
    > > > > > > > > This commit adds driver level support for the device tree
    > > > > > > > > property so that GPIO lines can be assigned friendly names.
    > > > > >
    > > > > > > > > This driver has three gpiochips with 32 gpios each. Core implementation
    > > > > > > >
    > > > > > > > implementation
    > > > > > > >
    > > > > > > >
    > > > > > > > > got gpio's repeated along each gpio chip if chip.names is not assigned.
    > > > > > > > > To avoid this behaviour driver will set this names as empty or
    > > > > > > >
    > > > > > > > the driver
    > > > > > > > these names
    > > > > > > >
    > > > > > > > > with desired friendly line names. Consider the following sample with
    > > > > > > > > minimal entries for the first chip with this patch changes applied:
    > > > > > > >
    > > > > > > > The same comment as per v1:
    > > > > > > >
    > > > > > > > Any idea why it's not a duplicate of
    > > > > > > > https://elixir.bootlin.com/linux/v5.13-rc7/C/ident/devprop_gpiochip_set_names,
    > > > > > > > and why the latter is not called in your case?
    > > > > > >
    > > > > > > The core properly calls this function but not in the way expected.
    > > > > > > This driver implements three banks of 32 gpios each internally using
    > > > > > > one gpiochip per bank, all of them in the same device. So the core
    > > > > > > code you are pointing out here duplicates the same names along the
    > > > > > > three gpiochips which is not the expected behaviour. So implementing
    > > > > > > in this way and setting names at least reserved avoids the core code
    > > > > > > to be run and also avoids the duplication getting expected behaviour
    > > > > > > for all the banks and each line friendly name.
    > > > > >
    > > > > > Isn't it the problem of how we supply fwnode in that case?
    > > > > > Another possibility is to fix DT (although I'm not sure it's now possible).
    > > > >
    > > > > Since the fwnode is the same for all banks of the same device, each bank
    > > > > repeats the first MTK_BANK_WIDTH label names in each bank.
    > > >
    > > > Can you point out the DT in question?
    > >
    > > https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/tree/drivers/staging/mt7621-dts/mt7621.dtsi?h=staging-next
    > >
    > > Gpio node:
    > >
    > > gpio: gpio@600 {
    > > #gpio-cells = <2>;
    > > #interrupt-cells = <2>;
    > > compatible = "mediatek,mt7621-gpio";
    > > gpio-controller;
    > > gpio-ranges = <&pinctrl 0 0 95>;
    > > interrupt-controller;
    > > reg = <0x600 0x100>;
    > > interrupt-parent = <&gic>;
    > > interrupts = <GIC_SHARED 12 IRQ_TYPE_LEVEL_HIGH>;
    > > };
    > >
    > > My overlay:
    > >
    > > &gpio {
    > > gpio-line-names = "", "", "", "",
    > > "", "", "SFP LOS", "extcon port5 PoE compat",
    > > "SFP module def0", "LED blue SFP", "SFP tx disable", "",
    > > "switch USB power", "mode", "", "buzzer",
    > > "LED blue pwr", "switch port5 PoE out", "reset";
    > > };
    > >
    > >
    > >
    > > >
    > > > > This commit populates the gc.names member of each bank from the
    > > > > device-tree node within the driver. This overrides the default behavior
    > > > > since devprop_gpiochip_set_names() will only be called if names is NULL.
    > > >
    > > > I believe this commit is not needed in the proposed (i.e. duplication) shape.
    > > > The fwnode supports primary and secondary ones. Thus, we may create a
    > > > pair of fwnodes when they will unify properties per device with
    > > > properties per child together (child is primary and device, i.e.
    > > > parent, is secondary).
    > >
    > > There are no child nodes, all the stuff is in the same parent node
    > > and, as I said, belongs to the same device but internally uses three
    > > gpiochips.
    >
    > And it can't be split into three children in the overlay?

    Original code before this being mainlined was using three children and
    I was told in the review that three children were not allowed:

    See https://patchwork.ozlabs.org/project/linux-gpio/patch/1527924610-13135-3-git-send-email-sergio.paracuellos@gmail.com/#1932827

    > Let's assume it can't, then the GPIO library function should be
    > refactored in a way that it takes parameters like base index for the
    > names and tries to satisfy the caller.

    Bartosz, Linus, any thoughts on this?

    >
    > > This case is pretty much the same as the following already
    > > added commit for gpio-brcmstb:
    > >
    > > https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/commit/drivers/gpio/gpio-brcmstb.c?id=5eefcaed501dd9e3933dbff58720244bd75ed90f
    >
    > This should be fixed accordingly.

    Obviously, the treatment should be the same, yes :)

    Best regards,
    Sergio Paracuellos
    >
    > --
    > With Best Regards,
    > Andy Shevchenko

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