Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754602AbcJZJ7V (ORCPT ); Wed, 26 Oct 2016 05:59:21 -0400 Received: from mail-it0-f65.google.com ([209.85.214.65]:40217 "EHLO mail-it0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753753AbcJZJ7Q (ORCPT ); Wed, 26 Oct 2016 05:59:16 -0400 MIME-Version: 1.0 In-Reply-To: <11644726.TmP4uu3h4l@ws-stein> References: <1477062035-30825-1-git-send-email-enric.balletbo@collabora.com> <11644726.TmP4uu3h4l@ws-stein> From: Enric Balletbo Serra Date: Wed, 26 Oct 2016 11:59:14 +0200 Message-ID: Subject: Re: [PATCH] gpio: mcp23s08: Add option to configure pullups. To: Alexander Stein Cc: Linus Walleij , Enric Balletbo i Serra , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-gpio@vger.kernel.org" , Rob Herring Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1532 Lines: 45 Hi Linus, 2016-10-24 8:13 GMT+02:00 Alexander Stein : > On Monday 24 October 2016 02:53:31, Linus Walleij wrote: >> On Fri, Oct 21, 2016 at 5:00 PM, Enric Balletbo i Serra >> >> 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 >> >> 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 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-gpio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html