From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jerome Brunet Subject: Re: [RFT PATCH v2] gpiolib: allow gpio irqchip to map irqs dynamically Date: Tue, 01 Aug 2017 10:03:34 +0200 Message-ID: <1501574614.2759.9.camel@baylibre.com> References: <20170721164900.7070-1-grygorii.strashko@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Linus Walleij , Grygorii Strashko , Bartosz Golaszewski Cc: "linux-gpio@vger.kernel.org" , "linux-kernel@vger.kernel.org" List-Id: linux-gpio@vger.kernel.org On Tue, 2017-08-01 at 09:52 +0200, Linus Walleij wrote: > On Fri, Jul 21, 2017 at 6:49 PM, Grygorii Strashko > wrote: > > > Now IRQ mappings are always created for all (allowed) GPIOs in gpiochip in > > gpiochip_irqchip_add_key() which goes against the idea of SPARSE_IRQ and, > > as result, leads to: > >  - increasing of memory consumption for IRQ descriptors most of which will > > never ever be used (espessially on platform with a high number of GPIOs). > > (sizeof(struct irq_desc) == 256 on my tested platforms) > >  - imposibility to use GPIO irqchip APIs by gpio drivers when HW implements > > GPIO IRQ functionality as IRQ crossbar/router which has only limited > > number of IRQ outputs (example from [1], all GPIOs can be mapped on only 8 > > IRQs). Sorry, I forgot to reply to this thread until now. This patch is generalization of create mapping in the gpio_to_irq, right ? So the issue of mapping left lying around until the gpio driver is unloaded is still there ? Having gpio_irq_prepare/gpio_irq_unprepare would solve that, I suppose (Again, sorry I could not send an RFC for this yet ...) > > > > Hence, remove static IRQ mapping code from gpiochip_irqchip_add_key() and > > instead replace irq_find_mapping() with irq_create_mapping() in > > gpiochip_to_irq(). Also add additional gpiochip_irqchip_irq_valid() calls > > in gpiochip_to_irq() and gpiochip_irq_map(). > > > > After this change gpio2irq mapping will happen the following way when GPIO > > irqchip APIs are used by gpio driver: > >  - IRQ mappings will be created statically if driver passes first_irq>0 > > vlaue in gpiochip_irqchip_add_key(). > >  - IRQ mappings will be created dynamically from gpio_to_irq() or > > of_irq_get(). > > > > Tested on am335x-evm and dra72-evm-revc. > > - dra72-evm-revc: number of created irq mappings decreased from 402 -> 135 > >   Mem savings 267*256 = 68352 (66kB) > > - am335x-evm: number of created irq mappings decreased from 188 -> 63 > >   Mem savings 125*256 = 32000 (31kB) > > > > [1] https://lkml.org/lkml/2017/6/15/428 > > Signed-off-by: Grygorii Strashko > > --- > > Changes in v2: > > - restored struct gpio_chip->irq_base to fix buld of gpio-mockup.c > > Applied this rather than v1. > > But maybe we should get rid of ->irq_base from gpio-mockup.c > and delete it, as the base is irqchip-internal. > > Bartosz what do you say? Do we need this in the mockup? > > Yours, > Linus Walleij