From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Chen-Yu Tsai <wens@csie.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] pinctrl: sunxi: Fix and simplify pin bank regulator handling
Date: Thu, 10 Jan 2019 16:28:51 +0100 [thread overview]
Message-ID: <20190110152851.g33mgpfgzeatj332@flea> (raw)
In-Reply-To: <20190110082633.6321-2-wens@csie.org>
[-- Attachment #1: Type: text/plain, Size: 1284 bytes --]
On Thu, Jan 10, 2019 at 04:26:33PM +0800, Chen-Yu Tsai wrote:
> The new per-pin-bank regulator handling code in the sunxi pinctrl driver
> has mismatched conditions for enabling and disabling the regulator: it
> is enabled each time a pin is requested, but only disabled when the
> pin-bank's reference count reaches zero.
>
> Since we are doing reference counting already, there's no need to enable
> the regulator each time a pin is requested. Instead we can just do it
> for the first requested pin of each pin-bank. Thus we can reverse the
> test and bail out early if it's not the first occurrence.
>
> Fixes: 9a2a566adb00 ("pinctrl: sunxi: Deal with per-bank regulators")
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
> I'm getting the feeling that the current code is prone to race
> conditions when pinctrl sets are actively switched during runtime, or
> gpios are requested and freed from userspace.
>
> Any ideas?
IIRC, I've looked into it when writing that patch and there's an upper
mutex that prevents request from being called multiple times at
once. Linus might prove me wrong though.
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]
next prev parent reply other threads:[~2019-01-10 15:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-10 8:26 [PATCH 1/2] pinctrl: sunxi: Increase size of regulator array Chen-Yu Tsai
2019-01-10 8:26 ` [PATCH 2/2] pinctrl: sunxi: Fix and simplify pin bank regulator handling Chen-Yu Tsai
2019-01-10 15:28 ` Maxime Ripard [this message]
2019-01-10 15:26 ` [PATCH 1/2] pinctrl: sunxi: Increase size of regulator array Maxime Ripard
2019-01-11 13:46 ` Chen-Yu Tsai
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190110152851.g33mgpfgzeatj332@flea \
--to=maxime.ripard@bootlin.com \
--cc=linus.walleij@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-gpio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=wens@csie.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).