linux-kernel - Re: [PATCH v2 3/3] dt-bindings: gpio: Add Nuvoton NPCM750 serial I/O expansion interface(SGPIO)

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Date:   Tue, 15 Nov 2022 10:55:33 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Jim Liu <jim.t90615@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>
Cc:     JJLIU0@...oton.com, KWLIU@...oton.com, brgl@...ev.pl,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, openbmc@...ts.ozlabs.org
Subject: Re: [PATCH v2 3/3] dt-bindings: gpio: Add Nuvoton NPCM750 serial I/O
 expansion interface(SGPIO)

On 14/11/2022 09:38, Jim Liu wrote:
> Hi Linus
> 
> Thanks for your reply.
> 
> let me explain the gpio pin as below:
> 
> Our sgpio module has 64 pins output and 64 pins input.
> Soc have 8 reg to control 64 output pins
> and  8 reg to control 64 input pins.
> so the pin is only for gpi or gpo.
> 
> The common property ngpio can be out or in.
> so i need to create d_out and d_in to control it.
> customers can set the number of output or input pins to use.

Aren't customers interested in specific pins, not the number? IOW, why
do you assume pins should be set to output in ascending order (e.g. 1, 2
and 3) and not in a flexible way?

> the driver will open the ports to use.
> ex: if  i set d_out=9   and d_in=20

Why 20 means three input ports? 9 opening two outputs could have sense
if it was a mask but you did not say it is a mask.



Best regards,
Krzysztof