linux-kernel - Re: [PATCH 1/1] pinctrl: stmfx: fix valid

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Date:   Thu, 7 Nov 2019 10:24:39 +0100
From:   Amelie DELAUNAY <amelie.delaunay@...com>
To:     Linus Walleij <linus.walleij@...aro.org>
CC:     Alexandre TORGUE <alexandre.torgue@...com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>
Subject: Re: [PATCH 1/1] pinctrl: stmfx: fix valid_mask init sequence

On 11/7/19 10:09 AM, Linus Walleij wrote:
> On Tue, Nov 5, 2019 at 4:14 PM Amelie DELAUNAY <amelie.delaunay@...com> wrote:
>> On 11/5/19 3:32 PM, Linus Walleij wrote:
>>> On Mon, Nov 4, 2019 at 11:09 AM Amelie Delaunay <amelie.delaunay@...com>
>>> wrote:
>>>
>>>> With stmfx_pinctrl_gpio_init_valid_mask callback, gpio_valid_mask was used
>>>> to initialize gpiochip valid_mask for gpiolib. But gpio_valid_mask was not
>>>> yet initialized. gpio_valid_mask required gpio-ranges to be registered,
>>>> this is the case after gpiochip_add_data call. But init_valid_mask
>>>> callback is also called under gpiochip_add_data. gpio_valid_mask
>>>> initialization cannot be moved before gpiochip_add_data because
>>>> gpio-ranges are not registered.
>>>
>>> Sorry but this doesn't add up, look at this call graph:
>>>
>>> gpiochip_add_data()
>>>     gpiochip_add_data_with_key()
>>>       gpiochip_alloc_valid_mask()
>>>       of_gpiochip_add()
>>>       of_gpiochip_add_pin_range()
>>>       gpiochip_init_valid_mask()
>>>
>>> So the .initi_valid_mask() is clearly called *after*
>>> of_gpiochip_add_pin_range() so this cannot be the real reason,
>>> provided that the ranges come from the device tree. AFAICT that
>>> is the case with the stmfx.
>>>
>>> Can you check and see if the problem is something else?
>>>
>>
>> stmfx_pinctrl_gpio_init_valid_mask uses pctl->gpio_valid_mask to
>> initialize gpiochip valid_mask.
>>
>> pctl->gpio_valid_mask is initialized in
>> stmfx_pinctrl_gpio_function_enable depending on gpio ranges.
>>
>> stmfx_pinctrl_gpio_function_enable is called after gpiochip_add_data
>> because it requires gpio ranges to be registered.
>>
>> So, in stmfx driver the call graph is
>>
>> stmfx_pinctrl_probe
>>     gpiochip_add_data()
>>       gpiochip_add_data_with_key()
>>         gpiochip_alloc_valid_mask()
>>         of_gpiochip_add()
>>         of_gpiochip_add_pin_range()
>>         gpiochip_init_valid_mask()
>>           stmfx_pinctrl_gpio_init_valid_mask (but pctl->gpio_valid_mask
>> is not yet initialized so gpiochip valid_mask is wrong)
>>     stmfx_pinctrl_gpio_function_enable (pctl->gpio_valid_mask is going to
>> be initialized thanks to gpio ranges)
>>
>> When consumer tries to take a pin (it is the case for the joystick on
>> stm32mp157c-ev1), it gets the following issue:
>> [    3.347391] irq: :soc:i2c@...13000:stmfx@42:stmfx-pin-controller
>> didn't like hwirq-0x0 to VIRQ92 mapping (rc=-6)
>> [    3.356418] irq: :soc:i2c@...13000:stmfx@42:stmfx-pin-controller
>> didn't like hwirq-0x1 to VIRQ92 mapping (rc=-6)
>> [    3.366512] irq: :soc:i2c@...13000:stmfx@42:stmfx-pin-controller
>> didn't like hwirq-0x2 to VIRQ92 mapping (rc=-6)
>> [    3.376671] irq: :soc:i2c@...13000:stmfx@42:stmfx-pin-controller
>> didn't like hwirq-0x3 to VIRQ92 mapping (rc=-6)
>> [    3.387169] irq: :soc:i2c@...13000:stmfx@42:stmfx-pin-controller
>> didn't like hwirq-0x4 to VIRQ92 mapping (rc=-6)
>> [    3.397065] gpio-keys joystick: Found button without gpio or irq
>> [    3.403041] gpio-keys: probe of joystick failed with error -22
>>
>> I can reword the commit message to make it clearer.
> 
> No need I understand it now, thanks for explaining!
> 
> We need to populate the valid mask some other way if you
> want to safeguard this, I don't know if the existing
> gpio-reserved-ranges would work? But it feels a bit unsafe
> if you actually determine this some other way.
> 

Before this patch, I made a "draft" version using the 
gpio-reserved-ranges property but then I had to use 
gpiochip_line_is_valid in pinconf_get/_set/_dbg_show in addition of 
pinctrl_find_gpio_range_from_pin... With an update of the bindings for 
optional property gpio-reserved-ranges.
I was not really fond of this solution, it sounded redundant.

Thanks for applying the patch.

Regards,
Amelie