linux-kernel - Re: [PATCH v2 1/1] gpio-f7188x: fix base values conflicts with other gpio pins

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Message-ID: <5428dcc3-bcaf-2fff-59db-62d3b3b45d17@163.com>
Date:   Tue, 30 May 2023 14:27:09 +0800
From:   "xingtong.wu" <xingtong_wu@....com>
To:     andy.shevchenko@...il.com, simon.guinot@...uanux.org
Cc:     Linus Walleij <linus.walleij@...aro.org>, brgl@...ev.pl,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        henning.schild@...mens.com, xingtong.wu@...mens.com
Subject: Re: [PATCH v2 1/1] gpio-f7188x: fix base values conflicts with other
 gpio pins

On 2023/5/30 06:24, andy.shevchenko@...il.com wrote:
> Mon, May 29, 2023 at 03:54:36PM +0200, simon.guinot@...uanux.org kirjoitti:
>> On Mon, May 29, 2023 at 03:03:28PM +0200, Linus Walleij wrote:
>>> On Mon, May 29, 2023 at 2:27 PM <simon.guinot@...uanux.org> wrote:
>>>
>>>> It would be nice if a pin number found in the device datasheet could
>>>> still be converted into a Linux GPIO number by adding the base of the
>>>> first bank.
>>>
>>> We actively discourage this kind of mapping because of reasons stated
>>> in drivers/gpio/TODO: we want dynamic number allocation to be the
>>> norm.
>>
>> Sure but it would be nice to have a dynamic base applied to a controller
>> (and not to each chip of this controller), and to respect the interval
>> between the chips (as stated in the controllers datasheets).
> 
> What you want is against the architecture. To fix this, you might change
> the architecture of the driver to have one chip for the controller, but
> it's quite questionable change. Also how can you guarantee ordering of
> the enumeration? You probably need to *disable* SMP on the boot time.
> This will still be fragile as long as GPIO chip can be unbound at run
> time. Order can be changed.
> 
> So, the patch is good and the correct way to go.
> 
> P.S. The root cause is that hardware engineers and documentation writers
> do not consider their hardware in the multi-tasking, multi-user general
> purpose operating system, such as Linux. I believe the ideal fix is to fix the
> documentation (datasheet).
> 

Hi,

Thanks for your review.

The direct reason of this patch is that when "modprobe gpio-f7188x",
it conflicts with INT34C6. I met this issue on an older kernel, but
could not remember which version exactly.

The error message is as the link below:
https://elixir.bootlin.com/linux/v6.3.2/source/drivers/gpio/gpiolib.c#L798

- XingTong Wu