All of lore.kernel.org
 help / color / mirror / Atom feed
From: Graeme Smecher <gsmecher@threespeedlogic.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>,
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
	gregory.clement@free-electrons.com
Subject: Re: [PATCH] gpio: pca953x: Don't flip bits on PCA957x GPIO expanders when probing them.
Date: Mon, 23 Sep 2013 09:36:39 -0400	[thread overview]
Message-ID: <524043E7.2050803@threespeedlogic.com> (raw)
In-Reply-To: <CACRpkdYWCFCtmF2_ORA5RRJudeNm9u+6ngMfcW8xrc+K2-Y3TQ@mail.gmail.com>

Hi,

On 23/09/13 06:57 AM, Linus Walleij wrote:
> On Fri, Sep 13, 2013 at 11:41 PM, Graeme Smecher
> <gsmecher@threespeedlogic.com>  wrote:
>
>> The pca957x driver supports a handful of I2C GPIO expanders from NXP, Maxim,
>> and TI. For the PCA9574 and PCA9575 devices only, the driver resets the GPIO
>> level and direction in the pca957x_probe function. This seems like the wrong
>> thing to do, since it can cause hardware bit twiddles during warm reboots when
>> the chip state and reset values don't match.
>>
>> This kind of initialization is best left upstream (in a bootloader) or
>> downstream (in userspace). It's also an inconsistency across devices supported
>> by this driver.
>>
>> This patch is NOT boot-tested: the SoC I'm  using is stuck on 2.6.37, and the
>> patch doesn't apply trivially.
>>
>> Signed-off-by: Graeme Smecher<gsmecher@threespeedlogic.com>
>> Acked-by: Haojian Zhuang<haojian.zhuang@gmail.com>
> Patch applied with Gregory's Tested-by tag!

Thanks all!

cheers,
Graeme

  reply	other threads:[~2013-09-23 13:39 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-13 21:41 [PATCH] gpio: pca953x: Don't flip bits on PCA957x GPIO expanders when probing them Graeme Smecher
2013-09-20 20:24 ` Linus Walleij
2013-09-20 20:37   ` Gregory CLEMENT
2013-09-20 21:06     ` Linus Walleij
2013-09-23  9:51       ` Gregory CLEMENT
2013-09-23 10:57 ` Linus Walleij
2013-09-23 13:36   ` Graeme Smecher [this message]
  -- strict thread matches above, loose matches on Subject: below --
2013-08-02 21:24 Graeme Smecher
2013-08-04 12:35 ` Haojian Zhuang
2013-09-09 18:14   ` Graeme Smecher

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=524043E7.2050803@threespeedlogic.com \
    --to=gsmecher@threespeedlogic.com \
    --cc=gregory.clement@free-electrons.com \
    --cc=haojian.zhuang@gmail.com \
    --cc=linus.walleij@linaro.org \
    --cc=linux-gpio@vger.kernel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.