From: Enric Balletbo Serra <eballetbo-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Alexander Stein
<alexander.stein-93q1YBGzJSMe9JSWTWOYM3xStJ4P+DSV@public.gmane.org>
Cc: Linus Walleij
<linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
Enric Balletbo i Serra
<enric.balletbo-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-gpio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-gpio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH] gpio: mcp23s08: Add option to configure pullups.
Date: Wed, 26 Oct 2016 11:59:14 +0200 [thread overview]
Message-ID: <CAFqH_53SSctH9Ms-0Zm5fhEgMtkWq_SP9VChY-QYV-qDLLj_WA@mail.gmail.com> (raw)
In-Reply-To: <11644726.TmP4uu3h4l@ws-stein>
Hi Linus,
2016-10-24 8:13 GMT+02:00 Alexander Stein
<alexander.stein-93q1YBGzJSMe9JSWTWOYM3xStJ4P+DSV@public.gmane.org>:
> On Monday 24 October 2016 02:53:31, Linus Walleij wrote:
>> On Fri, Oct 21, 2016 at 5:00 PM, Enric Balletbo i Serra
>>
>> <enric.balletbo-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org> wrote:
>> > Default is without pullups, but if property is specified in DT and the bit
>> > is set, set a pullup on GPIO-n.
>> >
>> > Signed-off-by: Enric Balletbo i Serra <enric.balletbo-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
>>
>> I don't generally like this.
>>
I tried to use the same approach as used in gpio-twl4030.c because is
what I knew before. Maybe you can point me to a better approach?
>> In device tree it is the consumer that specifies how the line is used,
>> not the producer (gpiochip).
>>
>> We currently only specify polarity, open drain and open source
>> for consumers though.
>>
>> And the entire pin control system came into being *exactly* because
>> Grant didn't like me adding these things to the GPIO drivers.
>>
>> So how many other things does the MCP support? Drive strength?
>> Schmitt trigger? Is there a datasheet?
>
> Some unsupported features (AFAIK):
> * Input polarity (IPOL register)
> * open-drain interrupt pin
> * pullup on pins (proposed patch)
>
> Datasheet is here: http://ww1.microchip.com/downloads/en/DeviceDoc/21919e.pdf
>
> Best regards,
> Alexander
>
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next prev parent reply other threads:[~2016-10-26 9:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-21 15:00 [PATCH] gpio: mcp23s08: Add option to configure pullups Enric Balletbo i Serra
2016-10-24 0:53 ` Linus Walleij
2016-10-24 6:13 ` Alexander Stein
2016-10-26 9:59 ` Enric Balletbo Serra [this message]
2016-10-27 12:22 ` Linus Walleij
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