From: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
To: Olof Johansson <olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org>,
Colin Cross <ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
Cc: Prashant Gaikwad
<pgaikwad-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH] ARM: tegra: fix U16 divider range check
Date: Fri, 03 Aug 2012 12:01:51 -0600 [thread overview]
Message-ID: <501C120F.60404@wwwdotorg.org> (raw)
In-Reply-To: <1343170214-28262-1-git-send-email-swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
On 07/24/2012 04:50 PM, Stephen Warren wrote:
> From: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>
> A U16 divider can divide a clock by 1..64K. However, the range-check
> in clk_div16_get_divider() limited the range to 1..256. Fix this. NVIDIA's
> downstream kernels already have the fixed range-check.
>
> In practice this is a problem on Whistler's I2C bus, which uses a bus
> clock rate of 100KHz (rather than the more common 400KHz on Tegra boards),
> which requires a HW module clock of 8*100KHz. The parent clock is 216MHz,
> leading to a desired divider of 270. Prior to conversion to the common
> clock framework, this range error was somehow ignored/irrelevant and
> caused no problems. However, the common clock framework evidently has
> more rigorous error-checking, so this failure causes the I2C bus to fail
> to operate correctly.
Applied to for-3.7/common-clk.
WARNING: multiple messages have this Message-ID (diff)
From: swarren@wwwdotorg.org (Stephen Warren)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: tegra: fix U16 divider range check
Date: Fri, 03 Aug 2012 12:01:51 -0600 [thread overview]
Message-ID: <501C120F.60404@wwwdotorg.org> (raw)
In-Reply-To: <1343170214-28262-1-git-send-email-swarren@wwwdotorg.org>
On 07/24/2012 04:50 PM, Stephen Warren wrote:
> From: Stephen Warren <swarren@nvidia.com>
>
> A U16 divider can divide a clock by 1..64K. However, the range-check
> in clk_div16_get_divider() limited the range to 1..256. Fix this. NVIDIA's
> downstream kernels already have the fixed range-check.
>
> In practice this is a problem on Whistler's I2C bus, which uses a bus
> clock rate of 100KHz (rather than the more common 400KHz on Tegra boards),
> which requires a HW module clock of 8*100KHz. The parent clock is 216MHz,
> leading to a desired divider of 270. Prior to conversion to the common
> clock framework, this range error was somehow ignored/irrelevant and
> caused no problems. However, the common clock framework evidently has
> more rigorous error-checking, so this failure causes the I2C bus to fail
> to operate correctly.
Applied to for-3.7/common-clk.
next prev parent reply other threads:[~2012-08-03 18:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-24 22:50 [PATCH] ARM: tegra: fix U16 divider range check Stephen Warren
2012-07-24 22:50 ` Stephen Warren
[not found] ` <1343170214-28262-1-git-send-email-swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-07-25 6:42 ` Prashant Gaikwad
2012-07-25 6:42 ` Prashant Gaikwad
2012-08-03 18:01 ` Stephen Warren [this message]
2012-08-03 18:01 ` Stephen Warren
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=501C120F.60404@wwwdotorg.org \
--to=swarren-3lzwwm7+weoh9zmkesr00q@public.gmane.org \
--cc=ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org \
--cc=linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org \
--cc=linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org \
--cc=pgaikwad-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org \
--cc=swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.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.