From: Sascha Hauer <s.hauer@pengutronix.de>
To: Igor Trevisan <igt1972@gmail.com>
Cc: barebox@lists.infradead.org
Subject: Re: iMX27 clock settings
Date: Wed, 15 Feb 2012 13:09:11 +0100 [thread overview]
Message-ID: <20120215120911.GB3852@pengutronix.de> (raw)
In-Reply-To: <CALQ+5adUP4qyf8+82s2NK6R3LbvjteuE-bkQ0iUdMG7X2LtxFQ@mail.gmail.com>
On Tue, Feb 14, 2012 at 04:10:08PM +0100, Igor Trevisan wrote:
> Hi,
>
> I'm working on a custom board based on iMX27L. Initially I worked with Redboot
> as Linux bootloader but now, I'm happily working with Barebox (2012.01.0)
> having replaced Redboot with it.
>
> Everithing is fine (thanks to the guys in the list for helping me!) but...
> I noticed that my Linux apps run more slowly within my system if it's
> started by Barebox
> then if it's started by Redbbot.
> I think it's a matter of internal clocks settings.
>
> I see that Redboot, for example, set:
> CSR=0x33F38107
> while Barebox does:
> writel(0x33F30307 | CSCR_MPLL_RESTART | CSCR_SPLL_RESTART, CSCR)
> That brings to CSR=0x33F30307 at the end of the PLLs restart procedure.
>
> Reading the Manual I can see that the differences between the two settings
> mean having an arm_clk that is 2/3 and an AHB_clk that's the half.
>
> Is there a particular reason for having these "slower configuration"?
One thing that might be interesting in such cases is the output of
the dump_clocks command.
Sascha
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next prev parent reply other threads:[~2012-02-15 12:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-14 15:10 Igor Trevisan
2012-02-15 9:15 ` Kamel BOUHARA
2012-02-15 11:10 ` Igor Trevisan
2012-02-15 9:29 ` Juergen Beisert
2012-02-15 12:09 ` Sascha Hauer [this message]
2012-02-15 14:59 ` Igor Trevisan
2012-02-15 16:06 ` Igor Trevisan
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