From: Vignesh R <vigneshr@ti.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] gpio: pca953x: Fix NBANK calculation for PCA9536
Date: Mon, 13 Jun 2016 14:34:04 +0530 [thread overview]
Message-ID: <575E7704.5090503@ti.com> (raw)
In-Reply-To: <CACRpkdYZEbefjr-iHT3yahkBovFuE2Ofvr8_Mr+X++pJSVwzfA@mail.gmail.com>
On Monday 13 June 2016 12:52 PM, Linus Walleij wrote:
> On Thu, Jun 9, 2016 at 7:32 AM, Vignesh R <vigneshr@ti.com> wrote:
>
>> NBANK() macro assumes that ngpios is a multiple of 8(BANK_SZ) and
>> hence results in 0 banks for PCA9536 which has just 4 gpios. This is
>> wrong as PCA9356 has 1 bank with 4 gpios. This results in uninitialized
>> PCA953X_INVERT register. Fix this by using DIV_ROUND_UP macro in
>> NBANK().
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Vignesh R <vigneshr@ti.com>
>
> Patch applied.
>
> Is this really a regression or affecting systems in development?
>
> Which machine/device tree makes this problematic?
>
I observed this on am335x-icev2 evm which is system in development.
Basically, variable with uninitialized value (junk) gets written to
PCA953X_INVERT register(in device_pca953x_init()) causing driver to
report wrong gpio pin status. So, this bug will affect any platform with
PCA9536 chip. Quick grep on arch/*/boot/dts/ folder shows one platform
already using pca9536 chip. Hence, I added Cc to stable kernel.
--
Regards
Vignesh
prev parent reply other threads:[~2016-06-13 9:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-09 5:32 [PATCH] gpio: pca953x: Fix NBANK calculation for PCA9536 Vignesh R
2016-06-13 7:22 ` Linus Walleij
2016-06-13 9:04 ` Vignesh R [this message]
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=575E7704.5090503@ti.com \
--to=vigneshr@ti.com \
--cc=gnurou@gmail.com \
--cc=linus.walleij@linaro.org \
--cc=linux-gpio@vger.kernel.org \
--cc=linux-kernel@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 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).