linux-kernel - Re: [PATCH] gpio: shared: handle the reset-gpios corner case

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Message-ID: <98c0f185-b0e0-49ea-896c-f3972dd011ca@packett.cool>
Date: Mon, 24 Nov 2025 20:05:24 -0300
From: Val Packett <val@...kett.cool>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Krzysztof Kozlowski <krzk@...nel.org>,
 Philipp Zabel <p.zabel@...gutronix.de>,
 Linus Walleij <linus.walleij@...aro.org>, linux-gpio@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH] gpio: shared: handle the reset-gpios corner case


On 11/24/25 12:36 PM, Bartosz Golaszewski wrote:
> On Mon, Nov 24, 2025 at 9:38 AM Bartosz Golaszewski <brgl@...ev.pl> wrote:
>> On Sun, Nov 23, 2025 at 2:03 AM Val Packett <val@...kett.cool> wrote:
>>>> ---
>>>> This is targetting linux-next where the reset-gpio driver is now using
>>>> the auxiliary bus and software nodes rather than the platform bus and
>>>> GPIO machine lookup. The bug is the same in both cases but the fix would
>>>> be completely different.
>>>> ---
>>>> [..]
>>> Tried applying only this, as well as this +
>>> https://lore.kernel.org/all/20251120-reset-gpios-swnodes-v7-0-a100493a0f4b@linaro.org/
>>> + https://lore.kernel.org/all/20251121135739.66528-1-brgl@bgdev.pl/ (on
>>> top of next-20251120) and the issue is still present.. am I missing
>>> something?
>> Can you try this branch?
>>
>>    https://github.com/brgl/linux test/gpiolib-shared-reset-gpio-fix
>>
>> I confirmed it works on my setup and fixes the problem with multiple
>> users of reset-gpio AND shared GPIOs enabled.
> Actually linux-next got updated with all the prerequisites so you can
> try this patch on top of next-20251124. I tested it and it works for
> me. If it still doesn't for you, can you enable GPIO debug messages
> and send me the entire kernel log?
>
> Bartosz

Rebased to next-20251124, still the same..

Here's a full dmesg: https://owo.packett.cool/lin/sound.gpio.dmesg

I even added a custom print to confirm the reason of the EBUSY:

[    9.233613] gpiolib: swnode: swnode_find_gpio: parsed 'reset-gpios' 
property of node 'node4[0]' - status (0)
[    9.233624] gpiolib_shared: Adding machine lookup entry for a shared 
GPIO for consumer reset.gpio.0, with key 'gpiolib_shared.proxy.8' and 
con_id 'reset'
[    9.233630] reset_gpio reset.gpio.0: using lookup tables for GPIO lookup
[    9.233640] gpio_shared_proxy gpiolib_shared.proxy.8: Shared GPIO 
requested, number of users: 1
[    9.233652] gpio_shared_proxy gpiolib_shared.proxy.8: Only one user 
of this shared GPIO, allowing to set direction to output with value 'low'
[    9.332317] reset_gpio reset.gpio.1: using swnode 'node5' for 'reset' 
GPIO lookup
[    9.332337] gpiolib: swnode: swnode_find_gpio: parsed 'reset-gpios' 
property of node 'node5[0]' - status (0)
[    9.332343] gpiolib_shared: Adding machine lookup entry for a shared 
GPIO for consumer reset.gpio.1, with key 'gpiolib_shared.proxy.8' and 
con_id 'reset'
[    9.332347] reset_gpio reset.gpio.1: using lookup tables for GPIO lookup
[    9.332353] gpio-856 (reset): gpiod_request_commit: flags 200043 
test_and_set_bit GPIOD_FLAG_REQUESTED -> EBUSY
[    9.332356] gpio-856 (reset): gpiod_request: status -16
[    9.332358] reset_gpio reset.gpio.1: error -EBUSY: Could not get 
reset gpios
[    9.332362] reset_gpio reset.gpio.1: probe with driver reset_gpio 
failed with error -16
[    9.441612] wcd938x_codec audio-codec: bound sdw:2:0:0217:010d:00:4 
(ops wcd_sdw_component_ops [snd_soc_wcd_common])
[    9.441644] wcd938x_codec audio-codec: bound sdw:3:0:0217:010d:00:3 
(ops wcd_sdw_component_ops [snd_soc_wcd_common])
[    9.445771] gpio_shared_proxy gpiolib_shared.proxy.8: Voted for value 
'high', effective value is 'high', number of votes for 'high': 1