[U-Boot-Users] flat tree clock setting
Hi.
Might it be nice if FT could use the calculated -- more likely to be correct timebase value? -dbu.
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 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
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.
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.
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
participants (4)
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David Updegraff -
Scott Wood -
Timur Tabi -
Wolfgang Denk