From: Michael Walle <michael@walle.cc> To: Bartosz Golaszewski <brgl@bgdev.pl>, Saravana Kannan <saravanak@google.com> Cc: Marcelo Roberto Jimenez <marcelo.jimenez@gmail.com>, Andrew Chant <achant@google.com>, Edmond Chung <edmondchung@google.com>, Geert Uytterhoeven <geert@linux-m68k.org>, Linus Walleij <linus.walleij@linaro.org>, "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>, regressions@lists.linux.dev, Stephen Rothwell <sfr@canb.auug.org.au>, stable <stable@vger.kernel.org>, Sergio Tanzilli <tanzilli@acmesystems.it>, Thierry Reding <treding@nvidia.com>, Vidya Sagar <vidyas@nvidia.com>, Will McVicker <willmcvicker@google.com>, Horatiu Vultur <horatiu.vultur@microchip.com>, Lars Povlsen <lars.povlsen@microchip.com> Subject: Re: [PATCH] gpio: Revert regression in sysfs-gpio (gpiolib.c) Date: Tue, 15 Mar 2022 16:45:01 +0100 [thread overview] Message-ID: <fe1ba600b2b30b4cba702d6aebdfda50@walle.cc> (raw) In-Reply-To: <CAMRc=MfH00YJv07TaiZ5z1w4gzqP5_8z9bKFcNU1Z37AVih4hQ@mail.gmail.com> [+ Saravana ] Am 2022-03-15 16:32, schrieb Bartosz Golaszewski: > On Mon, Mar 14, 2022 at 4:55 PM Michael Walle <michael@walle.cc> wrote: >> > Some GPIO lines have stopped working after the patch >> > commit 2ab73c6d8323f ("gpio: Support GPIO controllers without pin-ranges") >> > >> > And this has supposedly been fixed in the following patches >> > commit 89ad556b7f96a ("gpio: Avoid using pin ranges with !PINCTRL") >> > commit 6dbbf84603961 ("gpiolib: Don't free if pin ranges are not defined") >> > >> > But an erratic behavior where some GPIO lines work while others do not work >> > has been introduced. >> > >> > This patch reverts those changes so that the sysfs-gpio interface works >> > properly again. >> > >> > Signed-off-by: Marcelo Roberto Jimenez <marcelo.jimenez@gmail.com> >> >> This breaks the pinctrl-microchip-sgpio driver as far as I can see. >> >> I tried to debug it and this is what I have discovered so far: >> (1) the sgpio driver will use the gpio_stub_drv for its child nodes. >> Looks like a workaround, see [1]. >> (2) these will have an empty gpio range >> (3) with the changes of this patch, pinctrl_gpio_request() will now >> be called and will fail with -EPROBE_DEFER. >> >> I'm not exactly sure what to do here. Saravana Kannan once suggested >> to use devm_of_platform_populate() to probe the child nodes [2]. But >> I haven't found any other driver doing that. Oh I meant gpio/pinctrl drivers. > TI AEMIF driver (drivers/memory/ti-aemif.c) does something like this: > > 406 if (np) { > 407 for_each_available_child_of_node(np, child_np) { > 408 ret = of_platform_populate(child_np, NULL, > 409 dev_lookup, > dev); > 410 if (ret < 0) { > 411 of_node_put(child_np); > 412 goto error; > 413 } > 414 } > 415 } else if (pdata) { > 416 for (i = 0; i < pdata->num_sub_devices; i++) { > 417 pdata->sub_devices[i].dev.parent = dev; > 418 ret = > platform_device_register(&pdata->sub_devices[i]); > 419 if (ret) { > 420 dev_warn(dev, "Error register sub > device %s\n", > 421 > pdata->sub_devices[i].name); > 422 } > 423 } > 424 } > > A bunch of different devices (like NAND) get instantiated this way. > Would this work? I started to try this out, but then I was wondering if there weren't other gpio/pinctrl drivers with the same problem. And judging by the reports [1], I'd say there are. Then I wasn't sure if this is actually the correct fix here - or if that old workaround [2] doesn't work anymore because it might have that empty ranges "feature". To answer your question: I don't know. But I don't know if that is actually the correct way of fixing this either. >> Also, I'm not sure if there are any other other driver which get >> broken by this. I.e. ones falling into the gpio_stub_drv category. >> >> [1] >> https://lore.kernel.org/lkml/20210122193600.1415639-1-saravanak@google.com/ >> [2] >> https://lore.kernel.org/lkml/CAGETcx9PiX==mLxB9PO8Myyk6u2vhPVwTMsA5NkD-ywH5xhusw@mail.gmail.com/ >> >> -michael >> >> NB. this patch doesn't contain a Fixes tag. Was this on purpose? -michael [1] https://lore.kernel.org/lkml/20220314192522.GA3031157@roeck-us.net/ [2] https://lore.kernel.org/lkml/20210122193600.1415639-1-saravanak@google.com/
next prev parent reply other threads:[~2022-03-15 15:45 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-12-17 15:35 Marcelo Roberto Jimenez 2021-12-18 6:28 ` Thorsten Leemhuis 2021-12-20 14:57 ` Bartosz Golaszewski 2021-12-20 15:14 ` Geert Uytterhoeven 2021-12-20 19:24 ` Will McVicker 2021-12-20 20:41 ` Marcelo Roberto Jimenez 2021-12-20 20:41 ` Marcelo Roberto Jimenez 2021-12-20 20:41 ` Marcelo Roberto Jimenez 2022-01-10 7:02 ` Thorsten Leemhuis 2022-01-12 0:09 ` Marcelo Roberto Jimenez 2022-02-08 12:24 ` Thorsten Leemhuis 2022-02-17 19:11 ` Thierry Reding 2022-02-11 0:02 ` Linus Walleij 2022-02-11 22:36 ` Marcelo Roberto Jimenez 2022-02-12 16:54 ` Linus Walleij 2022-02-13 23:23 ` Marcelo Roberto Jimenez 2022-02-15 21:56 ` Linus Walleij 2022-02-16 14:40 ` Bartosz Golaszewski 2022-03-04 7:13 ` Thorsten Leemhuis 2022-03-07 9:58 ` Bartosz Golaszewski 2022-03-07 10:12 ` Thorsten Leemhuis 2022-05-20 9:12 ` Thorsten Leemhuis 2022-05-20 17:28 ` Marcelo Roberto Jimenez 2022-03-14 15:55 ` Michael Walle 2022-03-15 15:32 ` Bartosz Golaszewski 2022-03-15 15:45 ` Michael Walle [this message] 2022-03-17 8:37 ` Andy Shevchenko 2022-03-17 8:48 ` Michael Walle
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