[U-Boot-Users] flat tree clock setting

[U-Boot-Users] flat tree clock setting

[David Updegraff]

Hi.

Might it be nice if FT could use the calculated -- more likely to be
correct timebase value?
-dbu.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ft.patch
Type: text/x-patch
Size: 477 bytes
Desc: not available
Url : http://lists.denx.de/pipermail/u-boot/attachments/20061109/53628e5b/attachment.bin 

[U-Boot-Users] flat tree clock setting

[Timur Tabi]

David Updegraff wrote:
> Hi.
> 
> Might it be nice if FT could use the calculated -- more likely to be
> correct timebase value?

Wouldn't it be better to change get_tbclk() to look like this?

unsigned long get_tbclk(void)
{
#ifdef OF_TBCLK
	return OF_TBCLK
#else
	ulong tbclk;

	tbclk = (gd->bus_clk + 3L) / 4L;

	return tbclk;
#endif
}

And then change the ft_build.c code to always call get_tbclk()?

I haven't tried compiling the above code, but I think you all get the idea.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale

[U-Boot-Users] flat tree clock setting

[Scott Wood]

Timur Tabi wrote:
> Wouldn't it be better to change get_tbclk() to look like this?
> 
> unsigned long get_tbclk(void)
> {
> #ifdef OF_TBCLK
> 	return OF_TBCLK
> #else
> 	ulong tbclk;
> 
> 	tbclk = (gd->bus_clk + 3L) / 4L;
> 
> 	return tbclk;
> #endif
> }
> 
> And then change the ft_build.c code to always call get_tbclk()?

Are there any boards on which OF_TBCLK is (properly) set to something 
other than what get_tbclk() returns (ignoring the difference in 
rounding)?  I don't see any, nor can I think of a reason why such a 
difference should ever exist.  Perhaps OF_TBCLK should just be removed?

-Scott

[U-Boot-Users] flat tree clock setting

[Timur Tabi]

Scott Wood wrote:

> Are there any boards on which OF_TBCLK is (properly) set to something 
> other than what get_tbclk() returns (ignoring the difference in 
> rounding)?  

A search of the source code shows this:

File /temp/u-boot-83xx/include/configs/MPC8349EMDS.h
   332 2:#define OF_TBCLK		(bd->bi_busfreq / 4)
File /temp/u-boot-83xx/include/configs/MPC8349ITX.h
   395 2:#define OF_TBCLK		(bd->bi_busfreq / 4)
File /temp/u-boot-83xx/include/configs/MPC8360EMDS.h
   327 2:#define OF_TBCLK		(bd->bi_busfreq / 4)
File /temp/u-boot-83xx/include/configs/MPC8540ADS.h
   309 2:#define OF_TBCLK		(bd->bi_busfreq / 8)
File /temp/u-boot-83xx/include/configs/MPC8541CDS.h
   320 2:#define OF_TBCLK		(bd->bi_busfreq / 8)
File /temp/u-boot-83xx/include/configs/MPC8548CDS.h
   326 2:#define OF_TBCLK		(bd->bi_busfreq / 8)
File /temp/u-boot-83xx/include/configs/MPC8555CDS.h
   320 2:#define OF_TBCLK		(bd->bi_busfreq / 8)
File /temp/u-boot-83xx/include/configs/MPC8560ADS.h
   302 2:#define OF_TBCLK		(bd->bi_busfreq / 8)
File /temp/u-boot-83xx/include/configs/MPC8641HPCN.h
   269 2:#define OF_TBCLK	(bd->bi_busfreq / 4)
File /temp/u-boot-83xx/include/configs/stxxtc.h
   587 2:#define OF_TBCLK		(MPC8XX_HZ / 16)

Let's ignore the stxxtc for now, whatever that is.

On the 83xx, get_tbclk() returns "(gd->bus_clk + 3L) / 4L".  On 85xx and 86xx, 
it does this:

	get_sys_info(&sys_info);
	return ((sys_info.freqSystemBus + 7L) / 8L);

sys_info.freqSystemBus can be any number of things (see get_sys_info).

Well, it looks like they COULD always contain the same value.

> I don't see any, nor can I think of a reason why such a 
> difference should ever exist.  Perhaps OF_TBCLK should just be removed?

I think it's safe to say that *something* is redundant here, but I don't know 
yet what.  My vote would be for OF_TBCLK, though, if that works.

The only thing I know for sure is that all of this clock stuff is making me 
cuckoo.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale

[U-Boot-Users] flat tree clock setting

[Timur Tabi]

Scott Wood wrote:

> Are there any boards on which OF_TBCLK is (properly) set to something 
> other than what get_tbclk() returns (ignoring the difference in 
> rounding)?  I don't see any, nor can I think of a reason why such a 
> difference should ever exist.  Perhaps OF_TBCLK should just be removed?

Ok, I've done some more digging.

On PPC, bd->bi_busfreq is the same as gd->bus_clk.  In fact, there are a bunch 
of clocks in bd that are equal to similar values in gd.  The bd_t contains 
info that is passed to non-openfirmware versions of Linux, and the gd_t 
contains just general globally-defined data.

My guess is that anything which isn't directly used to boot non-OF Linux 
should use the gd structure.  So get_tbclk() does the right thing (although 
the rounding could be wrong), but OF_TBCLK should probably use gd->bus_clk.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale

[U-Boot-Users] flat tree clock setting

[Wolfgang Denk]

In message <eivm63$njd$1@sea.gmane.org> you wrote:
> 
> Might it be nice if FT could use the calculated -- more likely to be
> correct timebase value?

Coding style problems: indentation not by TAB.

Please cleanup and resubmit.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
I don't know if it's what you want, but it's what you get.  :-)
                      - Larry Wall in <10502@jpl-devvax.JPL.NASA.GOV>