From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Einar Vading Subject: SV: [PATCH RFC] gpio: new driver for a gpio simulator Date: Fri, 12 Oct 2018 08:02:09 +0000 Message-ID: <1539331329658.80509@axis.com> References: <20181008101356.5672-1-uwe@kleine-koenig.org> <20181009191121.r2tgc2oslwcwfhyn@pengutronix.de> <20181011081646.np2pte7eeohuyhh6@pengutronix.de>,<20181011094905.47onipkrzdp25psq@axis.com> In-Reply-To: <20181011094905.47onipkrzdp25psq@axis.com> Content-Language: sv-SE Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 To: Vincent Whitchurch , =?iso-8859-1?Q?Uwe_Kleine-K=F6nig?= Cc: Linus Walleij , Bartosz Golaszewski , Mark Rutland , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS , open list:GPIO SUBSYSTEM" , Rob Herring , Sascha Hauer List-ID: Since I was just evaluating the mockup driver to use in a test setup I'll g= ive my 2 cents.=0A= =0A= The benefit of the simulator is that we get the possibility to, if I unders= tand correctly, monitor an input for changes on the connected output. Sure,= we could also use ftrace but I like the idea of having the two connected G= PIOs. As a matter of fact I was just thinking about implementing something = that gave the same functionality for the mockup driver.=0A= =0A= What I like from the mockup driver is the possibility to have *many* gpios = on the same chip. We currently have a MCU I/O expander that gives us 110+ g= pios. So for us 64 GPIOs is really not enough.=0A= =0A= So neither driver works out of the box for us right now but both looks very= promising.=0A= =0A= Best Regards=0A= Einar=0A= ________________________________________=0A= Fr=E5n: linux-gpio-owner@vger.kernel.org = f=F6r Vincent Whitchurch =0A= Skickat: den 11 oktober 2018 11:49=0A= Till: Uwe Kleine-K=F6nig=0A= Kopia: Linus Walleij; Bartosz Golaszewski; Mark Rutland; open list:OPEN FIR= MWARE AND FLATTENED DEVICE TREE BINDINGS; open list:GPIO SUBSYSTEM; Rob Her= ring; Sascha Hauer=0A= =C4mne: Re: [PATCH RFC] gpio: new driver for a gpio simulator=0A= =0A= On Thu, Oct 11, 2018 at 10:16:46AM +0200, Uwe Kleine-K=F6nig wrote:=0A= > @Vincent: What is your usecase? I currently cannot imagine a use case=0A= > that can be done with the mockup driver but not with the simulator.=0A= =0A= I just needed a fake GPIO chip with a bunch of pins that I could use=0A= before I got the hardware with a real GPIO expander. In my case I only=0A= needed to test output so IIRC I didn't use the debugfs interface at all=0A= but instead used ftrace to check that my userspace triggered the correct=0A= operations on the "pins".=0A= =0A= So, yes, that would probably have worked just as well with this=0A= simulator instead of the mockup driver.=0A=