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From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [patch u-boot git arm/next] davinci: display correct	clock info
Date: Thu, 30 Apr 2009 09:18:02 +0200	[thread overview]
Message-ID: <20090430071802.GF31304@game.jcrosoft.org> (raw)
In-Reply-To: <200904292335.33059.david-b@pacbell.net>

On 23:35 Wed 29 Apr     , David Brownell wrote:
> On Wednesday 29 April 2009, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > my idea is more this
> > the lowlovel will init the pll (lowlevel_init.S or other stage bootloader)
> 
> Right ...
> 
> 
> > so instead of hardcoding the PPLDIV read it in the register
> > and then calculate the clock rate
> 
> That's all this code does:  read the PLL registers
> (and divider taps), and display settings in use by
> the current board.
yes but it's does not provice help full api to use it other where
in the code

> It happens that some SoCs have
> slightly different PLL configuration (like pre/post
> dividers) and feed important components (ARM, DSP,
> DDR) from different PLL dividers.
the PLL dividers are hardcoded why?
> 
> 
> > and it need it set the other non used clock 
> > depending on the IP used by u-boot (at runtime)
> 
> I don't know what you mean here.  PLL/tap configuration
> is distinct from clock distribution on the chip.
> 
> The cpu/arm926ejs/davinci/psc.c code handles clock
> distribution (and resets).  So for example the dm355
> chips leave most modules clocked but in reset, while
> the dm6446 leaves them unclocked and in reset ... so
> modules needed by u-boot get uniformly taken out of
> reset and clocked.
I known that's why I've in mind to set only the clock if
we use the drivers/IP at run time othewise let it off

>But that's *unrelated* to this
> PLL display code.
I agree this not for this patch but for an improvement

Best Regards,
J.

  reply	other threads:[~2009-04-30  7:18 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-29 22:38 [U-Boot] [patch u-boot git arm/next] davinci: display correct clock info David Brownell
2009-04-29 23:17 ` Jean-Christophe PLAGNIOL-VILLARD
2009-04-29 23:21   ` Ben Warren
2009-04-30  0:13   ` David Brownell
2009-04-30  6:10     ` Jean-Christophe PLAGNIOL-VILLARD
2009-04-30  6:35       ` David Brownell
2009-04-30  7:18         ` Jean-Christophe PLAGNIOL-VILLARD [this message]
2009-04-30  9:07           ` David Brownell
2009-05-01  1:23   ` David Brownell
2009-05-01 12:49     ` Jean-Christophe PLAGNIOL-VILLARD

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