[U-Boot] [patch u-boot git arm/next] davinci: display correct clock info

Jean-Christophe PLAGNIOL-VILLARD plagnioj at jcrosoft.com
Thu Apr 30 09:18:02 CEST 2009


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.


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