From: Alexander Sverdlin <alexander.sverdlin@gmail.com>
To: Hartley Sweeten <HartleyS@visionengravers.com>,
"nikita.shubin@maquefel.me" <nikita.shubin@maquefel.me>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
"bgolaszewski@baylibre.com" <bgolaszewski@baylibre.com>
Subject: Re: RFC Need advice on reworking gpio-ep93xx.c to DT support
Date: Mon, 22 Mar 2021 16:59:35 +0100 [thread overview]
Message-ID: <01b4dedd0f7efba749ebf598925886a6a69d5b41.camel@gmail.com> (raw)
In-Reply-To: <BYAPR01MB5621E8956FDBF8F194ABB598D0659@BYAPR01MB5621.prod.exchangelabs.com>
Hello Hartley,
On Mon, 2021-03-22 at 15:43 +0000, Hartley Sweeten wrote:
> > Showing only ports A, F and no interrupt capable C:
>
> Are you just going to drop the other GPIO ports?
>
> The EP93xx has eight 8-bit ports total (Ports A-H). Only 3 port support interrupts: A B and F. Posts A and B share a single interrupt and port F has an interrupt for each pin.
>
> Depending on the chip type (01, 02, 07, 12, or 15) not all the GPIOs are pinned out due to the chip pin count. But the registers exist so the current GPIO support always registers all the ports.
>
> Note that the GPIO banks are registered a bit goofy, Ports C and F are not in order. They have been that way since the original Cirrus "crater" code base. If I remember correctly this was somewhere
> back in the 2.6.x kernel. Please make sure the GPIO numbers stay the same so that any userspace code does not break.
I'm sceptical about this DT convertion.
Not only will it make the kernel bigger (back then is was a concern),
but they also do not guarantee any order of GPIOs with DT:
https://patchwork.kernel.org/comment/24009887/
--
Alexander Sverdlin.
next prev parent reply other threads:[~2021-03-22 16:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 12:19 RFC Need advice on reworking gpio-ep93xx.c to DT support nikita.shubin
2021-03-22 12:25 ` Linus Walleij
2021-03-22 15:43 ` Hartley Sweeten
2021-03-22 15:59 ` Alexander Sverdlin [this message]
2021-03-22 16:14 ` Hartley Sweeten
2021-03-22 16:48 ` nikita.shubin
2021-03-22 17:00 ` Alexander Sverdlin
2021-03-22 22:31 ` Arnd Bergmann
2021-03-23 6:57 ` Alexander Sverdlin
2021-03-23 8:45 ` Arnd Bergmann
2021-05-25 8:44 ` Geert Uytterhoeven
2021-03-23 8:21 ` Linus Walleij
2021-03-22 16:20 ` nikita.shubin
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