From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Alexandre Courbot <gnurou@gmail.com>,
Alexandre Courbot <acourbot@nvidia.com>,
Bartosz Golaszewski <brgl@bgdev.pl>,
Jonathan Corbet <corbet@lwn.net>,
Russell King <linux@armlinux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
"moderated list:ARM PORT" <linux-arm-kernel@lists.infradead.org>,
"open list:GENERIC INCLUDE/ASM HEADER FILES"
<linux-arch@vger.kernel.org>
Subject: Re: [PATCH] gpio: Allow user to customise maximum number of GPIOs
Date: Sun, 28 Aug 2022 09:06:35 +0000 [thread overview]
Message-ID: <515364a9-33a1-fafa-fdce-dc7dbd5bb7fb@csgroup.eu> (raw)
In-Reply-To: <CACRpkdZpwdP+1VitohznqRfhFGcLT2f+sQnmsRWwMBB3bobwAw@mail.gmail.com>
Le 26/08/2022 à 23:54, Linus Walleij a écrit :
> On Fri, Aug 26, 2022 at 5:08 PM Christophe Leroy
> <christophe.leroy@csgroup.eu> wrote:
>> Le 26/08/2022 à 15:49, Linus Walleij a écrit :
>>> On Thu, Aug 25, 2022 at 4:00 PM Christophe Leroy
>>> <christophe.leroy@csgroup.eu> wrote:
>>>
>>>>> Christophe? Will you take a stab at it?
>>>>
>>>> Which patch should I write ?
>>>
>>> One that removes CONFIG_ARCH_HAS_NR_GPIO entirely, then
>>> allocate bases for new GPIO chips from 0 and upward instead.
>>> And then see what happens.
>>>
>>
>> Ok, I can give it a try.
>
> Nice!
>
>> But what do I do with:
>>
>> drivers/gpio/gpio-aggregator.c: bitmap = bitmap_alloc(ARCH_NR_GPIOS,
>> GFP_KERNEL);
>
> That's just used locally in that driver to loop over the arguments to the
> aggregator (from the file in sysfs). I would set some arbitrary root
> like
> #define AGGREGATOR_MAX_GPIOS 512
> and just search/replace with that.
>
And what about gsta_gpio_setup() that requests base 0 with the following
comment:
/*
* ARCH_NR_GPIOS is currently 256 and dynamic allocation starts
* from the end. However, for compatibility, we need the first
* ConneXt device to start from gpio 0: it's the main chipset
* on most boards so documents and drivers assume gpio0..gpio127
*/
And I guess there might be other drivers like that (I found that one
because of its comment mentionning ARCH_NR_GPIOS.
Another solution could be to leave first GPIOs for static allocation,
and allocate dynamic ones from 256 or from 512 ?
Maybe in two steps:
- First step: Allocate dynamic from 256 upwards and add a pr_warn() for
all static allocations.
- Second step later: Allocate dynamic from 0 and forbid static allocation.
Any opinion ?
Christophe
next prev parent reply other threads:[~2022-08-28 9:06 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-09 10:40 [PATCH] gpio: Allow user to customise maximum number of GPIOs Christophe Leroy
2022-08-11 19:57 ` H. Peter Anvin
2022-08-12 21:58 ` Andy Shevchenko
2022-08-12 23:21 ` H. Peter Anvin
2022-08-17 17:21 ` Christophe Leroy
2022-08-17 17:46 ` Arnd Bergmann
2022-08-18 6:00 ` Christophe Leroy
2022-08-18 8:25 ` Arnd Bergmann
2022-08-18 9:33 ` Linus Walleij
2022-08-18 9:47 ` Arnd Bergmann
2022-08-18 11:13 ` Linus Walleij
2022-08-18 11:33 ` Arnd Bergmann
2022-08-18 12:25 ` Linus Walleij
2022-08-18 12:46 ` Arnd Bergmann
2022-08-18 13:11 ` Christophe Leroy
2022-08-25 13:36 ` Linus Walleij
2022-08-25 14:00 ` Christophe Leroy
2022-08-26 13:49 ` Linus Walleij
2022-08-26 15:08 ` Christophe Leroy
2022-08-26 21:54 ` Linus Walleij
2022-08-28 9:06 ` Christophe Leroy [this message]
2022-08-28 10:04 ` Arnd Bergmann
2022-08-30 7:58 ` Davide Ciminaghi
2022-08-31 13:32 ` Linus Walleij
2022-08-31 14:12 ` Davide Ciminaghi
2022-08-31 21:07 ` Andy Shevchenko
2022-08-31 21:48 ` Davide Ciminaghi
2022-08-30 8:33 ` Alessandro Rubini
2022-08-30 9:03 ` Christophe Leroy
2022-08-28 11:35 ` Linus Walleij
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