linux-kernel - Re: [PATCH v4 2/2] fpga: Add support for Lattice iCE40 FPGAs

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Message-ID: <f3c6dac1-bf10-c945-3e8a-9146e07253fd@airwebreathe.org.uk>
Date:   Mon, 31 Oct 2016 10:58:16 -0600
From:   Joel Holdsworth <joel@...webreathe.org.uk>
To:     Rob Herring <robh@...nel.org>
Cc:     atull@...nsource.altera.com, moritz.fischer@...us.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-spi@...r.kernel.org
Subject: Re: [PATCH v4 2/2] fpga: Add support for Lattice iCE40 FPGAs

Hi Rob,

Thanks for taking the time review the patches.

>>  .../bindings/fpga/lattice-ice40-fpga-mgr.txt       |  23 +++
>
> It's preferred that bindings are a separate patch.

Can you just clarify a little? I'm happy to split the patch up, but I 
don't understand how it could work without the bindings. For example, in 
ice40_fpga_probe, I have to get the GPIOs with devm_gpiod_get for the 
driver to work.

Maybe I'm missing something. Or do you just mean the documentation?

>
> -gpios is preferred.
>
> Please state direction and polarity.

Thanks, I'll fix that up.

>
>> +- creset_b-gpio:	GPIO connected to CRESET_B pin. Note that CRESET_B is
>
> Don't use '_'. In this case, I'd just do cresetb-gpios.

So the pin is called CRESET_B in the datasheet. I think the _B refers to 
the active-low polarity of the line.

So I would think it should be creset-b-gpios or creset-gpios. I'm not so 
convinced cresetb-gpios is ideal, but it's a minor point.

>
>> +			treated as an active-low output because the signal is
>> +			treated as an enable signal, rather than a reset. This
>
> Though for enable signals, enable-gpios is fairly standard even if that
> deviates from the pin name.

I would think that would just confuse the user, unless they dig out the 
binding docs. The FPGA doesn't have an enable pin, and it's not at all 
obvious that a "reset" pin means "enable" in this driver.

Again, if you're adamant this is the correct convention it's no problem 
to make the change - just seems weird to me. What do you think?

Thanks
Joel