Re: [PATCHv4 2/2] Add a GPIO driver for Altera FPGA Manager Fabric I/O

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Fri, Oct 20, 2017 at 4:40 PM, Bernd Edlinger
<bernd.edlinger@xxxxxxxxxx> wrote:
> On 10/20/17 10:10, Linus Walleij wrote:

>>> +       err = bgpio_init(&port->bgc, gpio->dev, 4, dat, NULL, NULL,
>>> +                        NULL, NULL, 0);
>>
>> But all you add is input-only GPIO chips. Also for the output ports.
>>
>
> Well actually this allows both input and output,
> but while the input port could be written by accident,
> the hardware does the right thing and ignores the write cycle.
>
> The other parameters of bgpio_input are for devices with
> explicit set- and reset-signals, and configurable
> output-direction etc, which I don't have.

Ah! You're right. With just one register it becomes one of these that
read and write into that register, simply. Sorry for my ignorance.

I would prefer if you set the flag BGPIOF_NO_OUTPUT on the input
only version though. Semantics may matter to the mmio gpio core.

Yours,
Linus Walleij
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