From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grygorii Strashko Subject: Re: Lack of suspend/resume/shutdown ordering between GPIO providers and consumers Date: Wed, 25 Apr 2018 14:29:59 -0500 Message-ID: References: <03711276-d854-7f87-f2e2-c64716b09dbe@ti.com> <206bea0c-dbba-1bc3-d13b-dbc41d12c08b@gmail.com> <7602f017-4abe-52ae-a112-7165076e2d89@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Florian Fainelli , linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, dmitry.torokhov@gmail.com, jeffy.chen@rock-chips.com, enric.balletbo@collabora.com, josephl@nvidia.com, opendmb@gmail.com, rjw@rjwysocki.net List-Id: devicetree@vger.kernel.org On 04/25/2018 02:10 PM, Grygorii Strashko wrote: > > > On 04/25/2018 01:57 PM, Florian Fainelli wrote: >> On 04/25/2018 11:47 AM, Grygorii Strashko wrote: >>> >>> >>> On 04/25/2018 01:29 PM, Florian Fainelli wrote: >>>> On 04/25/2018 11:06 AM, Grygorii Strashko wrote: >>>>> >>>>> >>>>> On 04/24/2018 05:58 PM, Florian Fainelli wrote: >>>>>> Hi Linus, Rafael, all >>>>>> >>>>>> Our GPIO controller driver: gpio-brcmstb.c has a shutdown callback >>>>>> which >>>>>> gets invoked when the system is brought into poweroff aka S5. So far so >>>>>> good, except that we also wish to use gpio_keys.c as a possible wake-up >>>>>> source, so we may have a number of GPIO pins declared as gpio-keys that >>>>>> allow the system to wake-up from deep slumber. >>>>>> >>>>>> Recently we noticed that we could easily get into a state where >>>>>> gpio-brcmstb.c::brcmstb_gpio_shutdown() gets called first, and then >>>>>> gpio_keys.c::gpio_keys_suspend() gets called later, which is too >>>>>> late to >>>>>> have the enable_irq_wake() call do anything sensible since we have >>>>>> suspend its parent interrupt controller before. This is completely >>>>>> expected unfortunately because these two drivers are both platform >>>>>> device instances with no connection to one another except via Device >>>>>> Tree and the use of the GPIOLIB APIs. >>>>> >>>>> You can take a look at device_link_add() and Co. >>>> >>>> OK, though that requires a struct device references, so while I could >>>> certainly resolve the device_node -> struct device that corresponds to >>>> the GPIO provider , that poses a number of issues: >>>> >>>> - not all struct device_node have a corresponding struct device >>>> reference (e.g: clock providers, interrupt controllers, and possibly >>>> other custom drivers), though in this case, they most likely do have one >>>> >>>> - resolving a struct device associated with a struct device_node is >>>> often done in a "bus" specific way, e.g: of_find_device_by_node(), so if >>>> the GPIO provider is e.g: i2c_device, pci_device etc. etc. this might >>>> not work that easily >>>> >>>> I think this is what Dmitry just indicated in his email as well. >>>> >>>>> >>>>> But it's little bit unclear what exactly you have issue with: >>>>> - shutdown >>>>> - suspend >>>>> >>>>> above are different (at least as it was before) and gpio-brcmstb.c >>>>>   brcmstb_gpio_shutdown() should not be called as part of suspend !? >>>>> may be you mean brcmstb_gpio_suspend? >>>> >>>> The issue exists with shutdown (through the use of "poweroff"), that is >>>> confirmed, but I cannot see how it does not exist with any suspend state >>>> as well, for the same reason that the ordering is not strictly enforced. >>> >>> Sry, but it still required some clarification :( - poweroff calls >>> device_shutdown() which, in turn, should not call .suspend(), so >>> how have you got both .shutdown() and .suspend() callbacks called during >>> poweroff? Am I missing smth? >> >> You are missing me telling you the whole story, sorry I got confused, >> but you are absolutely right these are separate lists and on >> poweroff/shutdown only ->shutdown() is called. What I had missed in the >> report I was submitted was that there was a .shutdown() callback being >> added to gpio_keys.c, which of course, because it's an Android based >> project is not in the upstream Linux kernel. >> >> The problem does remain valid though AFAICT. Thanks Grygorii! >> > > Thanks. But that means you should not see this problem :( > There is devices_kset_move_last() call in really_probe() which moves probed dev > at the end of kset, and gpio_keys should never be probed before gpio-brcmstb because > both devm_fwnode_get_gpiod_from_child() and devm_gpio_request_one() expected to return > -EPROBE_DEFER otherwise. > > Theoretically issue still might happen with suspend. > FYI https://lkml.org/lkml/2015/9/10/218 -- regards, -grygorii