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Date: Mon, 24 Oct 2016 08:13:54 +0200 From: Alexander Stein <alexander.stein@...tec-electronic.com> To: Linus Walleij <linus.walleij@...aro.org> Cc: Enric Balletbo i Serra <enric.balletbo@...labora.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>, Rob Herring <robh+dt@...nel.org> Subject: Re: [PATCH] gpio: mcp23s08: Add option to configure pullups. 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@...labora.com> 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@...labora.com> > > I don't generally like this. > > 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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