2020-09-03 15:03:14

by Lars Povlsen

[permalink] [raw]
Subject: [PATCH v2 1/3] dt-bindings: pinctrl: Add bindings for pinctrl-mchp-sgpio driver

This adds DT bindings for the Microsemi/Microchip SGPIO controller,
bindings microchip,sparx5-sgpio, mscc,ocelot-sgpio and
mscc,luton-sgpio.

Signed-off-by: Lars Povlsen <[email protected]>
---
.../pinctrl/microchip,sparx5-sgpio.yaml | 88 +++++++++++++++++++
include/dt-bindings/gpio/mchp-sgpio.h | 19 ++++
2 files changed, 107 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pinctrl/microchip,sparx5-sgpio.yaml
create mode 100644 include/dt-bindings/gpio/mchp-sgpio.h

diff --git a/Documentation/devicetree/bindings/pinctrl/microchip,sparx5-sgpio.yaml b/Documentation/devicetree/bindings/pinctrl/microchip,sparx5-sgpio.yaml
new file mode 100644
index 000000000000..25a50ba9e893
--- /dev/null
+++ b/Documentation/devicetree/bindings/pinctrl/microchip,sparx5-sgpio.yaml
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pinctrl/microchip,sparx5-sgpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microsemi/Microchip Serial GPIO controller
+
+maintainers:
+ - Lars Povlsen <[email protected]>
+
+description: |
+ By using a serial interface, the SIO controller significantly extend
+ the number of available GPIOs with a minimum number of additional
+ pins on the device. The primary purpose of the SIO controllers is to
+ connect control signals from SFP modules and to act as an LED
+ controller.
+
+properties:
+ $nodename:
+ pattern: "gpio"
+
+ compatible:
+ enum:
+ - microchip,sparx5-sgpio
+ - mscc,ocelot-sgpio
+ - mscc,luton-sgpio
+
+ clocks:
+ maxItems: 1
+
+ gpio-controller: true
+
+ '#gpio-cells':
+ description: GPIO consumers must specify four arguments, first the
+ port number, then the bit number, then a input/output flag and
+ finally the GPIO flags (from include/dt-bindings/gpio/gpio.h).
+ The dt-bindings/gpio/mchp-sgpio.h file define manifest constants
+ PIN_INPUT and PIN_OUTPUT.
+ const: 4
+
+ gpio-ranges:
+ maxItems: 1
+
+ microchip,sgpio-port-ranges:
+ description: This is a sequence of tuples, defining intervals of
+ enabled ports in the serial input stream. The enabled ports must
+ match the hardware configuration in order for signals to be
+ properly written/read to/from the controller holding
+ registers. Being tuples, then number of arguments must be
+ even. The tuples mast be ordered (low, high) and are
+ inclusive. Arguments must be between 0 and 31.
+ $ref: /schemas/types.yaml#/definitions/uint32-array
+ minItems: 2
+ maxItems: 64
+
+ microchip,sgpio-frequency:
+ description: The sgpio controller frequency (Hz). This dictates
+ the serial bitstream speed, which again affects the latency in
+ getting control signals back and forth between external shift
+ registers. The speed must be no larger than half the system
+ clock, and larger than zero.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 1
+ default: 12500000
+
+required:
+ - compatible
+ - clocks
+ - gpio-controller
+ - '#gpio-cells'
+ - gpio-ranges
+ - microchip,sgpio-port-ranges
+
+examples:
+ - |
+ sgpio2: gpio@1101036c {
+ compatible = "microchip,sparx5-sgpio";
+ pinctrl-0 = <&sgpio0_pins>;
+ pinctrl-names = "default";
+ reg = <0x1101036c 0x100>;
+ clocks = <&sys_clk>;
+ gpio-controller;
+ gpio-ranges = <&sgpio0 0 0 192>;
+ #gpio-cells = <4>;
+ microchip,sgpio-port-ranges = <0 0 16 18 28 31>;
+ microchip,sgpio-frequency = <25000000>;
+ };
diff --git a/include/dt-bindings/gpio/mchp-sgpio.h b/include/dt-bindings/gpio/mchp-sgpio.h
new file mode 100644
index 000000000000..61b8aa75d870
--- /dev/null
+++ b/include/dt-bindings/gpio/mchp-sgpio.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * This header provides constants for binding the Microchip SGPIO
+ * driver.
+ *
+ */
+
+#ifndef _DT_BINDINGS_GPIO_MCHP_SGPIO_H
+#define _DT_BINDINGS_GPIO_MCHP_SGPIO_H
+
+#include <dt-bindings/gpio/gpio.h>
+
+/* mchp-sgpio specific pin type defines */
+#undef PIN_OUTPUT
+#undef PIN_INPUT
+#define PIN_OUTPUT 0
+#define PIN_INPUT 1
+
+#endif
--
2.27.0


2020-09-12 10:52:10

by Linus Walleij

[permalink] [raw]
Subject: Re: [PATCH v2 1/3] dt-bindings: pinctrl: Add bindings for pinctrl-mchp-sgpio driver

Hi Lars,

thanks for your patch!

On Thu, Sep 3, 2020 at 3:35 PM Lars Povlsen <[email protected]> wrote:

> This adds DT bindings for the Microsemi/Microchip SGPIO controller,

What I do not understand is why this GPIO controller is placed in the
bindings of the pin controllers? Do you plan to add pin control
properties to the bindings in the future?

> +description: |
> + By using a serial interface, the SIO controller significantly extend
> + the number of available GPIOs with a minimum number of additional
> + pins on the device. The primary purpose of the SIO controllers is to
> + connect control signals from SFP modules and to act as an LED
> + controller.

This doesn't sound like it will ever be pin control?

> + gpio-controller: true
> +
> + '#gpio-cells':
> + description: GPIO consumers must specify four arguments, first the
> + port number, then the bit number, then a input/output flag and
> + finally the GPIO flags (from include/dt-bindings/gpio/gpio.h).
> + The dt-bindings/gpio/mchp-sgpio.h file define manifest constants
> + PIN_INPUT and PIN_OUTPUT.
> + const: 4

I do not follow this new third input/output flag at all.

- If it is a property of the hardware, it is something the driver should
handle by determining which hardware it is from the compatible
string.

- If it is a configuration it should be turned into something that is generic
and useful for *all* GPIO controllers. If it is pin config it should use
the pinconf bindings rather than shortcuts like this, but I think it is
something the driver can do as an effect of the pin being requested
as input or output in the operating system, depending on who the
consumer is. Linux for example has GPIOD_OUT_LOW,
GPIOD_OUT_HIGH, GPIOD_IN, GPIOD_ASIS...

- Is it not just a hog? We have bindings for those.

> + microchip,sgpio-port-ranges:
> + description: This is a sequence of tuples, defining intervals of
> + enabled ports in the serial input stream. The enabled ports must
> + match the hardware configuration in order for signals to be
> + properly written/read to/from the controller holding
> + registers. Being tuples, then number of arguments must be
> + even. The tuples mast be ordered (low, high) and are
> + inclusive. Arguments must be between 0 and 31.
> + $ref: /schemas/types.yaml#/definitions/uint32-array
> + minItems: 2
> + maxItems: 64

And you are *absolutely sure* that you can't just figure this out
from the compatible string? Or add a few compatible strings for
the existing variants?

> + microchip,sgpio-frequency:
> + description: The sgpio controller frequency (Hz). This dictates
> + the serial bitstream speed, which again affects the latency in
> + getting control signals back and forth between external shift
> + registers. The speed must be no larger than half the system
> + clock, and larger than zero.
> + $ref: /schemas/types.yaml#/definitions/uint32
> + minimum: 1
> + default: 12500000

I understand why you need this binding now, OK.

> +/* mchp-sgpio specific pin type defines */
> +#undef PIN_OUTPUT
> +#undef PIN_INPUT
> +#define PIN_OUTPUT 0
> +#define PIN_INPUT 1

I'm not a fan of this. It seems like something that should be set in
response to the gpiochip callbacks .direction_input and
.direction_output callbacks.

Yours,
Linus Walleij

2020-09-13 19:13:18

by Lars Povlsen

[permalink] [raw]
Subject: Re: [PATCH v2 1/3] dt-bindings: pinctrl: Add bindings for pinctrl-mchp-sgpio driver


Linus Walleij writes:

> Hi Lars,
>
> thanks for your patch!

You're welcome - thank you for you taking time to review it!

>
> On Thu, Sep 3, 2020 at 3:35 PM Lars Povlsen <[email protected]> wrote:
>
>> This adds DT bindings for the Microsemi/Microchip SGPIO controller,
>
> What I do not understand is why this GPIO controller is placed in the
> bindings of the pin controllers? Do you plan to add pin control
> properties to the bindings in the future?

I have made provisions for some of the generic pinconf parameters, and
since the controller also has support for some alternate modes like
(syncronized) blink at various rates, I thought I better add it as
pinctrl straight away.

>
>> +description: |
>> + By using a serial interface, the SIO controller significantly extend
>> + the number of available GPIOs with a minimum number of additional
>> + pins on the device. The primary purpose of the SIO controllers is to
>> + connect control signals from SFP modules and to act as an LED
>> + controller.
>
> This doesn't sound like it will ever be pin control?

above.

>
>> + gpio-controller: true
>> +
>> + '#gpio-cells':
>> + description: GPIO consumers must specify four arguments, first the
>> + port number, then the bit number, then a input/output flag and
>> + finally the GPIO flags (from include/dt-bindings/gpio/gpio.h).
>> + The dt-bindings/gpio/mchp-sgpio.h file define manifest constants
>> + PIN_INPUT and PIN_OUTPUT.
>> + const: 4
>
> I do not follow this new third input/output flag at all.
>

Its actually a sort of bank address, since the individual "pins" are
unidirectional.

The PIN_INPUT/PIN_OUTPUT is defined in similar fashion in other pinctrl
binding header files... I can drop the define and use, but as it will be
used to address individual pins, I think it adds to readability.

Like this (excerpts from a DT with a switchdev driver using SFP's and
LED's on sgpio):

/{
leds {
compatible = "gpio-leds";
led@0 {
label = "eth60:yellow";
gpios = <&sgpio1 28 0 PIN_OUTPUT GPIO_ACTIVE_LOW>;
default-state = "off";
};
...
};
};

&axi {
sfp_eth60: sfp-eth60 {
compatible = "sff,sfp";
i2c-bus = <&i2c152>;
tx-disable-gpios = <&sgpio2 28 0 PIN_OUTPUT GPIO_ACTIVE_LOW>;
rate-select0-gpios = <&sgpio2 28 1 PIN_OUTPUT GPIO_ACTIVE_HIGH>;
los-gpios = <&sgpio2 28 0 PIN_INPUT GPIO_ACTIVE_HIGH>;
mod-def0-gpios = <&sgpio2 28 1 PIN_INPUT GPIO_ACTIVE_LOW>;
tx-fault-gpios = <&sgpio2 28 2 PIN_INPUT GPIO_ACTIVE_HIGH>;
};
...
};

> - If it is a property of the hardware, it is something the driver should
> handle by determining which hardware it is from the compatible
> string.
>
> - If it is a configuration it should be turned into something that is generic
> and useful for *all* GPIO controllers. If it is pin config it should use
> the pinconf bindings rather than shortcuts like this, but I think it is
> something the driver can do as an effect of the pin being requested
> as input or output in the operating system, depending on who the
> consumer is. Linux for example has GPIOD_OUT_LOW,
> GPIOD_OUT_HIGH, GPIOD_IN, GPIOD_ASIS...
>
> - Is it not just a hog? We have bindings for those.

I hope the above shed some light on this.

>
>> + microchip,sgpio-port-ranges:
>> + description: This is a sequence of tuples, defining intervals of
>> + enabled ports in the serial input stream. The enabled ports must
>> + match the hardware configuration in order for signals to be
>> + properly written/read to/from the controller holding
>> + registers. Being tuples, then number of arguments must be
>> + even. The tuples mast be ordered (low, high) and are
>> + inclusive. Arguments must be between 0 and 31.
>> + $ref: /schemas/types.yaml#/definitions/uint32-array
>> + minItems: 2
>> + maxItems: 64
>
> And you are *absolutely sure* that you can't just figure this out
> from the compatible string? Or add a few compatible strings for
> the existing variants?
>

Yes, this really needs to be configured for each board individually -
and cant be probed. It defines how the bitstream to/from the shift
registers is constructed/demuxed.

>> + microchip,sgpio-frequency:
>> + description: The sgpio controller frequency (Hz). This dictates
>> + the serial bitstream speed, which again affects the latency in
>> + getting control signals back and forth between external shift
>> + registers. The speed must be no larger than half the system
>> + clock, and larger than zero.
>> + $ref: /schemas/types.yaml#/definitions/uint32
>> + minimum: 1
>> + default: 12500000
>
> I understand why you need this binding now, OK.
>
>> +/* mchp-sgpio specific pin type defines */
>> +#undef PIN_OUTPUT
>> +#undef PIN_INPUT
>> +#define PIN_OUTPUT 0
>> +#define PIN_INPUT 1
>
> I'm not a fan of this. It seems like something that should be set in
> response to the gpiochip callbacks .direction_input and
> .direction_output callbacks.
>

As I tried to explain above, its a part of the pin address - aka bank
selector - whether your are accessing the input or the output side. And
since the directions have totally different - and concurrent - use, they
need to be individually addressed, not "configured".

In the example presented, sgpio2-p28b0 IN is loss-of-signal, and the
OUT is the sfp tx-disable control.

> Yours,
> Linus Walleij

---Lars

--
Lars Povlsen,
Microchip

2020-09-30 09:25:01

by Linus Walleij

[permalink] [raw]
Subject: Re: [PATCH v2 1/3] dt-bindings: pinctrl: Add bindings for pinctrl-mchp-sgpio driver

Hi Lars,

thanks for working on this!

On Sun, Sep 13, 2020 at 9:11 PM Lars Povlsen <[email protected]> wrote:

> > What I do not understand is why this GPIO controller is placed in the
> > bindings of the pin controllers? Do you plan to add pin control
> > properties to the bindings in the future?
>
> I have made provisions for some of the generic pinconf parameters, and
> since the controller also has support for some alternate modes like
> (syncronized) blink at various rates, I thought I better add it as
> pinctrl straight away.

OK fair enough let's keep the bindings here.

BTW the latter function sounds like some kind of PWM?

> >> + gpio-controller: true
> >> +
> >> + '#gpio-cells':
> >> + description: GPIO consumers must specify four arguments, first the
> >> + port number, then the bit number, then a input/output flag and
> >> + finally the GPIO flags (from include/dt-bindings/gpio/gpio.h).
> >> + The dt-bindings/gpio/mchp-sgpio.h file define manifest constants
> >> + PIN_INPUT and PIN_OUTPUT.
> >> + const: 4
> >
> > I do not follow this new third input/output flag at all.
>
> Its actually a sort of bank address, since the individual "pins" are
> unidirectional.

I'm a bit confused here...
The standard advice for any "banked" GPIOs is to represent
each "bank" as a separate node (with a corresponding gpio_chip
in the Linux kernel). Then you can just use the standard
bindings to pick a line from one of these nodes.

> The PIN_INPUT/PIN_OUTPUT is defined in similar fashion in other pinctrl
> binding header files... I can drop the define and use, but as it will be
> used to address individual pins, I think it adds to readability.

Hmmm. What makes these names expecially confusing is the
Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml defines:
input-enable
input-disable
output-enable
output-high
output-low

In the Linux kernel further there is:
include/linux/pinctrl/pinconf-generic.h that defines:
PIN_CONFIG_INPUT_ENABLE
PIN_CONFIG_OUTPUT_ENABLE
PIN_CONFIG_OUTPUT

Since you are using the pin control framework this gets really
hard to hash out.

I don't really understand why it is needed.

> Like this (excerpts from a DT with a switchdev driver using SFP's and
> LED's on sgpio):
>
> /{
> leds {
> compatible = "gpio-leds";
> led@0 {
> label = "eth60:yellow";
> gpios = <&sgpio1 28 0 PIN_OUTPUT GPIO_ACTIVE_LOW>;
> default-state = "off";
> };
> ...
> };
> };

If what you intend to achieve is to make the GPIO come up in output mode,
you can either just have the driver do that as needed by the consumer.
If you absolutely have to do it in the device tree, then implement
pin control (pin config) and have it something like this:

leds {
compatible = "gpio-leds";
pinctrl-names = "default";
pinctrl-0 = <&my_led_pinctrl>;
led@0 {
label = "eth60:yellow";
gpios = <&sgpio1 28 GPIO_ACTIVE_LOW>;
default-state = "off";
};
...

my_led_pinctrl: pinctrl-led {
pins = "gpio95"; // Just an example way of referring to the pin
bias-disable;
output-enable;
};
};

> >> + microchip,sgpio-port-ranges:
> >> + description: This is a sequence of tuples, defining intervals of
> >> + enabled ports in the serial input stream. The enabled ports must
> >> + match the hardware configuration in order for signals to be
> >> + properly written/read to/from the controller holding
> >> + registers. Being tuples, then number of arguments must be
> >> + even. The tuples mast be ordered (low, high) and are
> >> + inclusive. Arguments must be between 0 and 31.
> >> + $ref: /schemas/types.yaml#/definitions/uint32-array
> >> + minItems: 2
> >> + maxItems: 64
> >
> > And you are *absolutely sure* that you can't just figure this out
> > from the compatible string? Or add a few compatible strings for
> > the existing variants?
>
> Yes, this really needs to be configured for each board individually -
> and cant be probed. It defines how the bitstream to/from the shift
> registers is constructed/demuxed.

And you have considered the option of simply letting the driver
check which board we are then? The property at the very
top of the device tree.

if (of_machine_is_compatible("my_board")) {
....
} else if (of_machine_is_compatible("my_other_board")) {
....
}

So that you simply use the board compatible string to determine
this?

> >> +/* mchp-sgpio specific pin type defines */
> >> +#undef PIN_OUTPUT
> >> +#undef PIN_INPUT
> >> +#define PIN_OUTPUT 0
> >> +#define PIN_INPUT 1
> >
> > I'm not a fan of this. It seems like something that should be set in
> > response to the gpiochip callbacks .direction_input and
> > .direction_output callbacks.
> >
>
> As I tried to explain above, its a part of the pin address - aka bank
> selector - whether your are accessing the input or the output side. And
> since the directions have totally different - and concurrent - use, they
> need to be individually addressed, not "configured".
>
> In the example presented, sgpio2-p28b0 IN is loss-of-signal, and the
> OUT is the sfp tx-disable control.

I suspect the proper way to do it is to create one node for
the input side and one node for the output side and also create
two different gpio chips in the kernel.

my-device {
compatible = "my-device";
gpioin: input-gpio {
....
};
gpioout: output-gpio {
....
};
};

Note: I didn't think over the naming in this example.

You will need code in your driver to parse the subnodes and
populate two gpio_chips.

Yours,
Linus Walleij

2020-10-05 08:23:33

by Lars Povlsen

[permalink] [raw]
Subject: Re: [PATCH v2 1/3] dt-bindings: pinctrl: Add bindings for pinctrl-mchp-sgpio driver


Linus Walleij writes:

> Hi Lars,
>
> thanks for working on this!
>
> On Sun, Sep 13, 2020 at 9:11 PM Lars Povlsen <[email protected]> wrote:
>
>> > What I do not understand is why this GPIO controller is placed in the
>> > bindings of the pin controllers? Do you plan to add pin control
>> > properties to the bindings in the future?
>>
>> I have made provisions for some of the generic pinconf parameters, and
>> since the controller also has support for some alternate modes like
>> (syncronized) blink at various rates, I thought I better add it as
>> pinctrl straight away.
>
> OK fair enough let's keep the bindings here.
>
> BTW the latter function sounds like some kind of PWM?

Yes, it has PWM functionality as well.

>
>> >> + gpio-controller: true
>> >> +
>> >> + '#gpio-cells':
>> >> + description: GPIO consumers must specify four arguments, first the
>> >> + port number, then the bit number, then a input/output flag and
>> >> + finally the GPIO flags (from include/dt-bindings/gpio/gpio.h).
>> >> + The dt-bindings/gpio/mchp-sgpio.h file define manifest constants
>> >> + PIN_INPUT and PIN_OUTPUT.
>> >> + const: 4
>> >
>> > I do not follow this new third input/output flag at all.
>>
>> Its actually a sort of bank address, since the individual "pins" are
>> unidirectional.
>
> I'm a bit confused here...
> The standard advice for any "banked" GPIOs is to represent
> each "bank" as a separate node (with a corresponding gpio_chip
> in the Linux kernel). Then you can just use the standard
> bindings to pick a line from one of these nodes.

Yes, that seems to be a good model.

>
>> The PIN_INPUT/PIN_OUTPUT is defined in similar fashion in other pinctrl
>> binding header files... I can drop the define and use, but as it will be
>> used to address individual pins, I think it adds to readability.
>
> Hmmm. What makes these names expecially confusing is the
> Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml defines:
> input-enable
> input-disable
> output-enable
> output-high
> output-low
>
> In the Linux kernel further there is:
> include/linux/pinctrl/pinconf-generic.h that defines:
> PIN_CONFIG_INPUT_ENABLE
> PIN_CONFIG_OUTPUT_ENABLE
> PIN_CONFIG_OUTPUT
>
> Since you are using the pin control framework this gets really
> hard to hash out.
>

Yes, as the pins are fixed-function, the "input-enable", "input-disable"
and "output-enable" are not really useful.

> I don't really understand why it is needed.
>
>> Like this (excerpts from a DT with a switchdev driver using SFP's and
>> LED's on sgpio):
>>
>> /{
>> leds {
>> compatible = "gpio-leds";
>> led@0 {
>> label = "eth60:yellow";
>> gpios = <&sgpio1 28 0 PIN_OUTPUT GPIO_ACTIVE_LOW>;
>> default-state = "off";
>> };
>> ...
>> };
>> };
>
> If what you intend to achieve is to make the GPIO come up in output mode,
> you can either just have the driver do that as needed by the consumer.
> If you absolutely have to do it in the device tree, then implement
> pin control (pin config) and have it something like this:
>
> leds {
> compatible = "gpio-leds";
> pinctrl-names = "default";
> pinctrl-0 = <&my_led_pinctrl>;
> led@0 {
> label = "eth60:yellow";
> gpios = <&sgpio1 28 GPIO_ACTIVE_LOW>;
> default-state = "off";
> };
> ...
>
> my_led_pinctrl: pinctrl-led {
> pins = "gpio95"; // Just an example way of referring to the pin
> bias-disable;
> output-enable;
> };
> };

No, the PIN_OUTPUT is purely for adressing. But as you suggested, I'll
split the into separate nodes. That will eliminate the "PIN_OUTPUT" and
the bindings header.

>
>> >> + microchip,sgpio-port-ranges:
>> >> + description: This is a sequence of tuples, defining intervals of
>> >> + enabled ports in the serial input stream. The enabled ports must
>> >> + match the hardware configuration in order for signals to be
>> >> + properly written/read to/from the controller holding
>> >> + registers. Being tuples, then number of arguments must be
>> >> + even. The tuples mast be ordered (low, high) and are
>> >> + inclusive. Arguments must be between 0 and 31.
>> >> + $ref: /schemas/types.yaml#/definitions/uint32-array
>> >> + minItems: 2
>> >> + maxItems: 64
>> >
>> > And you are *absolutely sure* that you can't just figure this out
>> > from the compatible string? Or add a few compatible strings for
>> > the existing variants?
>>
>> Yes, this really needs to be configured for each board individually -
>> and cant be probed. It defines how the bitstream to/from the shift
>> registers is constructed/demuxed.
>
> And you have considered the option of simply letting the driver
> check which board we are then? The property at the very
> top of the device tree.
>
> if (of_machine_is_compatible("my_board")) {
> ....
> } else if (of_machine_is_compatible("my_other_board")) {
> ....
> }

No, board-specific code is undesireable, as our customers should be able
to design own boards without driver changes.

>
> So that you simply use the board compatible string to determine
> this?
>
>> >> +/* mchp-sgpio specific pin type defines */
>> >> +#undef PIN_OUTPUT
>> >> +#undef PIN_INPUT
>> >> +#define PIN_OUTPUT 0
>> >> +#define PIN_INPUT 1
>> >
>> > I'm not a fan of this. It seems like something that should be set in
>> > response to the gpiochip callbacks .direction_input and
>> > .direction_output callbacks.
>> >
>>
>> As I tried to explain above, its a part of the pin address - aka bank
>> selector - whether your are accessing the input or the output side. And
>> since the directions have totally different - and concurrent - use, they
>> need to be individually addressed, not "configured".
>>
>> In the example presented, sgpio2-p28b0 IN is loss-of-signal, and the
>> OUT is the sfp tx-disable control.
>
> I suspect the proper way to do it is to create one node for
> the input side and one node for the output side and also create
> two different gpio chips in the kernel.
>
> my-device {
> compatible = "my-device";
> gpioin: input-gpio {
> ....
> };
> gpioout: output-gpio {
> ....
> };
> };
>
> Note: I didn't think over the naming in this example.
>
> You will need code in your driver to parse the subnodes and
> populate two gpio_chips.

Yes, I will modify the driver to use separate nodes for each direction.

Thank you for your comments, it is highly appreciated.

---Lars

>
> Yours,
> Linus Walleij

--
Lars Povlsen,
Microchip