From: matt@grid-net.com (Matt Burtch)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/1] ARM iMX28: incorrect frac/div calculation
Date: Thu, 22 Mar 2012 16:05:01 -0700 [thread overview]
Message-ID: <1332457501-8153-1-git-send-email-matt@grid-net.com> (raw)
The frac and div values in _CLK_SET_RATE are calculated incorrectly
for some clock rates ie. CPU clk of 454.73MHz, 392.72MHz, 261.81Mhz,
etc.
Now the frac and div values which result in the closest actual clock
rate to that requested is selected. Also there are no limitations
on what frac values can be used, as long as they fall in the valid
(18 < frac < 35) range.
Tested on custom iMX28 board.
Signed-off-by: Matt Burtch <matt@grid-net.com>
---
arch/arm/mach-mxs/clock-mx28.c | 8 ++------
1 files changed, 2 insertions(+), 6 deletions(-)
diff --git a/arch/arm/mach-mxs/clock-mx28.c b/arch/arm/mach-mxs/clock-mx28.c
index 5d68e41..a058b99 100644
--- a/arch/arm/mach-mxs/clock-mx28.c
+++ b/arch/arm/mach-mxs/clock-mx28.c
@@ -354,19 +354,15 @@ static int name##_set_rate(struct clk *clk, unsigned long rate) \
} \
for (d = 1; d <= div_max; d++) { \
f = parent_rate * 18 / d / rate; \
- if ((parent_rate * 18 / d) % rate) \
- f++; \
if (f < 18 || f > 35) \
continue; \
\
calc_rate = parent_rate * 18 / f / d; \
- if (calc_rate > rate) \
- continue; \
\
- if (rate - calc_rate < diff) { \
+ if (abs(rate - calc_rate) < diff) { \
frac = f; \
div = d; \
- diff = rate - calc_rate; \
+ diff = abs(rate - calc_rate); \
} \
\
if (diff == 0) \
--
1.7.5.4
next reply other threads:[~2012-03-22 23:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-22 23:05 Matt Burtch [this message]
2012-03-23 2:52 ` [PATCH 1/1] ARM iMX28: incorrect frac/div calculation Shawn Guo
2012-03-23 18:38 ` Matt Burtch
2012-03-23 7:13 ` Lothar Waßmann
2012-03-23 18:38 ` Matt Burtch
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=1332457501-8153-1-git-send-email-matt@grid-net.com \
--to=matt@grid-net.com \
--cc=linux-arm-kernel@lists.infradead.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).