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    SubjectRe: about pca955x led driver gpio management
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    Hi Cedric,

    Andrea seems to come across a real issue. We might proceed with the
    contribution of his patch without your review and possibly
    Tested-by, but it would be nevertheless beneficial if we had them.

    Best regards,
    Jacek Anaszewski

    On 10/17/2017 11:16 AM, Andrea Scian - DAVE Embedded Systems wrote:
    >
    >> On 10/17/2017 10:20 AM, Andrea Scian - DAVE Embedded Systems wrote:
    >>>
    >>> Il 17/10/2017 10:18, Cédric Le Goater ha scritto:
    >>>> On 10/17/2017 09:36 AM, Andrea Scian - DAVE Embedded Systems wrote:
    >>>>> Dear all,
    >>>>>
    >>>>> I'm working on an iMX6 based board with a PCA9555 which is used
    >>>>> both to drive LEDs and manage some GPIOs.
    >>>> The PCA9555 chip and the PCA955[0-3] chips have different control
    >>>> registers. You need a different led driver for it.
    >>>
    >>> My typo sorry, as you can see in the device tree below, I'm using
    >>> pca9551
    >>
    >> ok.
    >>
    >> You might want to take a look at how we mixed gpios and leds on the
    >> witherspoon
    >> system using pca9552 chips. we added a gpio-leds binding.
    >>
    >> https://github.com/openbmc/linux/blob/dev-4.10/arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts
    >>
    >
    > understood: you configure all pins of PCA955x as GPIOs and the map the
    > one you need as led with gpio-leds binding.
    >
    > However to me this is a kind of workaround or, at least, there's nothing
    > about this limitation into the devicetree binding (in fact, IMHO, the
    > device tree binding example will just fail)
    >
    > I wrote the attached patch which should fix the issue and allow a more
    > generic approach. WDYT?
    >
    > (in case it looks good, I'll send the patch in the correct way)
    >
    >
    > Kind Regards,
    >
    > Andrea
    >
    >>>
    >>>>> My current kernel is quite old (4.1.15) but I've found Cédric
    >>>>> patches on mainline and backported to this old revision.
    >>>>>
    >>>>> I'm facing an issue with it, because it seems that it fails when
    >>>>> it's used in a mixed (led/gpios) environment.
    >>>>>
    >>>>> E.g.: let's say that I have one led connected to LED0 output and
    >>>>> one GPIO connected at LED1 output.
    >>>>>
    >>>>> I define it as
    >>>>>
    >>>>> pca9551: pca9551@60 {
    >>>>> compatible = "nxp,pca9551";
    >>>>> reg = <0x60>;
    >>>>> #address-cells = <1>;
    >>>>> #size-cells = <0>;
    >>>>> #gpio-cells = <1>;
    >>>>>
    >>>>> led@0 {
    >>>>> label = "led0";
    >>>>> reg = <0>;
    >>>>> linux,default-trigger =
    >>>>> "none";
    >>>>> };
    >>>>> gpio@1 {
    >>>>> label = "gpio1";
    >>>>> reg = <1>;
    >>>>> type = <2>; /* GPIO */
    >>>>> };
    >>>>> };
    >>>>>
    >>>>> At boot it's probed as
    >>>>>
    >>>>> root@sbc-lynx:~# dmesg | grep pca
    >>>>> [ 5.315425] leds-pca955x 5-0060: leds-pca955x: Using pca9551
    >>>>> 8-bit LED driver at slave address 0x60
    >>>>> [ 5.350349] leds-pca955x 5-0060: gpios 511...511
    >>>>>
    >>>>> But I cannot access it:
    >>>>>
    >>>>> root@sbc-lynx:~# echo 511 > /sys/class/gpio/export
    >>>>> -sh: echo: write error: Device or resource busy
    >>>>>
    >>>>> Because for pca955x_gpio_request_pin() this is at offset 0 (in fact
    >>>>> is the first gpio registered of this gpio_chip) but it's the index
    >>>>> 1 inside pca955x->leds[]
    >>>>>
    >>>>> Am I missing something? (maybe I made a mistake in my backport
    >>>>> and/or I'm missing some patches about the GPIO subsystems).
    >>>>>
    >>>>> If I'm right I think I can send a patch to fix this (I'm thinking
    >>>>> about having an array of GPIO index to map offset ->
    >>>>> pca955x->leds[] index or just register all pins as GPIOs and then
    >>>>> just report the busy state)
    >>>>>
    >>>>> WDYT?
    >>>>>
    >>>>> Kind Regards,
    >>>>>
    >>>
    >>

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