From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: Re: [PATCH 2/2] gpio: sch: Add interrupt support Date: Wed, 24 Apr 2019 16:13:57 +0300 Message-ID: <20190424131357.GJ2654@lahna.fi.intel.com> References: <20190424084259.GW2654@lahna.fi.intel.com> <7e328b7e-f4f0-851a-4152-a9ffd058201c@siemens.com> <20190424094506.GA2654@lahna.fi.intel.com> <292e6eff-82cc-6e4d-925b-77a60399e2e0@siemens.com> <20190424100130.GB2654@lahna.fi.intel.com> <1200464b-f969-ebc2-ae82-1f8ca98aaca1@siemens.com> <20190424103306.GC2654@lahna.fi.intel.com> <9377620b-d74a-04d9-a51e-8590400b1c0f@siemens.com> <20190424104613.GD2654@lahna.fi.intel.com> <761ed823-58f4-d166-c415-6b100b1fe615@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <761ed823-58f4-d166-c415-6b100b1fe615@siemens.com> Sender: linux-kernel-owner@vger.kernel.org To: Jan Kiszka Cc: Andy Shevchenko , Linus Walleij , Bartosz Golaszewski , Linux Kernel Mailing List , linux-gpio@vger.kernel.org, linux-acpi@vger.kernel.org, "Rafael J. Wysocki" List-Id: linux-acpi@vger.kernel.org On Wed, Apr 24, 2019 at 02:41:02PM +0200, Jan Kiszka wrote: > On 24.04.19 12:46, Mika Westerberg wrote: > > On Wed, Apr 24, 2019 at 12:39:35PM +0200, Jan Kiszka wrote: > > > On 24.04.19 12:33, Mika Westerberg wrote: > > > > On Wed, Apr 24, 2019 at 12:19:02PM +0200, Jan Kiszka wrote: > > > > > > I think what you want is "GPIO signaled ACPI event". It works so that > > > > > > you declare _AEI method below the GPIO controller listing the GPIOs you > > > > > > want to trigger events for and then either _Lxx, _Exx or _EVT method for > > > > > > each of them under the same controller. GPIO core then handles it > > > > > > automatically when you register the GPIO chip. See also > > > > > > acpi_gpiochip_request_interrupts(). > > > > > > > > > > Right, that is was I read as well. Let's assume I would be able to patch the > > > > > tables: Would I describe all the logic of this patch in ACPI terms? Where to > > > > > enable interrupts, how to dispatch the SCI event, how to acknowledge it > > > > > etc.? Will it also take care of locking? (BTW, my locking seems to have some > > > > > remaining inconsistency, on second look.) > > > > > > > > The GPIO core would then take care of it by requesting the GPIO in > > > > question and dispatching to the correct event handler. In this patch you > > > > just leave out the SCI part and only implement the irqchip like you did > > > > already. > > > > > > Could you point me to a gpio driver that works like that already? Would be > > > easier to learn that from an example. That infrastructure with all its > > > different modes is seriously complex and not very well documented. > > > > Pretty much all drivers under drivers/pinctrl/intel. > > OK... that's a purely descriptive way. So, provided we had such ACPI table > entries, that plus some corresponding pinctrl driver would obsolete > gpio-sch.c? Or are there other reason than historical ones for having > gpio-*ch.c drivers around? No they are for different hardware. The GPIO core will parse necessary ACPI entires when any GPIO driver (with ACPI description) calls gpiochip_add_data() or any of the wrappers. > > > > > And even if that were possible, we would be back to the square of existing > > > > > devices without those definitions. If this were a recent chipset, I would > > > > > say, "go, fix future firmware versions". But this one is legacy. > > > > > > > > Is it fixing some real issue with these legacy platforms? I mean without > > > > the patch some GPE event is not handled properly? It was not clear to me > > > > from the commit message. > > > > > > > Without that patch, you are forced to poll for event changes in your > > > application, timer-driven. There are application that cannot process these > > > GPIOs because they lack such logic (mraa with node-red-node-intel-gpio is a > > > public example). > > > > But those are using the GPIOs via sysfs or the char device which should > > work without the SCI handling part of your patch, no? > > They work via sysfs. How would the char dev compensate the missing interrupt > support? I'm trying to say that for the sysfs access (well or char dev) you should not need the sch_sci_handler() thing that is in your current patch.