Re: [Gumstix-users] ARM clock specs

[Akram Hameed <AkramH@aq...>]

-----Original Message-----
From: Rick Rogers [mailto:Richard.Rogers@...] 
Sent: 23. December 2010 02:46
To: gumstix-users@...
Subject: [Gumstix-users] ARM clock specs

Hello,

I noticed the Overo FE (COM with wifi and bluetooth) is spec'd to 600MHz

for the ARM core, while the Overo Fire (without wifi and bluetooth) is 
spec'd at 720MHz for the ARM core.  What is the reason for this 
difference?  The nominal ARM frequency for the OMAP is 500MHz at OPP3 
(if I remember correctly)- how is the higher clock rate achieved?  Does 
the DSP core automatically follow (ie, does an increase in ARM freq 
automatically increase the DSP clock)?

Thanks,
Rick


G'day Rick,

TI document SPRS507B (can get it here:
http://focus.ti.com/lit/ds/symlink/omap3530.pdf) suggests recommended
Operating conditions for the OMAP chip. You'll want section 3.3,
specifically.

In a nutshell, however, the FE part will suffer significant silicon
degradation if you attempt to run 'hot' in extreme temperatures.
You could theoretically counter this with a heat exchange mechanism.  

DSP clock tracks ARM clock, far as I recall.  

If you'd like to try bumping your clock up a bit, you can set the
'mpurate' variable in uboot.

e.g. @ the uboot prompt. 
#setenv mpurate 600
#saveenv
#boot

Then once you're logged into the kernel:  
root@...:~# cat /proc/cpuinfo 
Hardware        : Gumstix Overo
Revision        : 0020
Serial          : 0000000000000000
root@...:~# cat /proc/cpuinfo
Processor       : ARMv7 Processor rev 3 (v7l)
BogoMIPS        : 597.64
Features        : swp half thumb fastmult vfp edsp thumbee neon vfpv3
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x1
CPU part        : 0xc08
CPU revision    : 3

Hardware        : Gumstix Overo
Revision        : 0020
Serial          : 0000000000000000


Cheers,
Akram.

[Gumstix-users] ARM clock specs

[Rick Rogers <Richard.Rogers@jh...>]

Hello,

I noticed the Overo FE (COM with wifi and bluetooth) is spec'd to 600MHz 
for the ARM core, while the Overo Fire (without wifi and bluetooth) is 
spec'd at 720MHz for the ARM core.  What is the reason for this 
difference?  The nominal ARM frequency for the OMAP is 500MHz at OPP3 
(if I remember correctly)- how is the higher clock rate achieved?  Does 
the DSP core automatically follow (ie, does an increase in ARM freq 
automatically increase the DSP clock)?

Thanks,
Rick

Re: [Gumstix-users] ARM clock specs

[Akram Hameed <AkramH@aq...>]

-----Original Message-----
From: Rick Rogers [mailto:Richard.Rogers@...] 
Sent: 23. December 2010 02:46
To: gumstix-users@...
Subject: [Gumstix-users] ARM clock specs

Hello,

I noticed the Overo FE (COM with wifi and bluetooth) is spec'd to 600MHz

for the ARM core, while the Overo Fire (without wifi and bluetooth) is 
spec'd at 720MHz for the ARM core.  What is the reason for this 
difference?  The nominal ARM frequency for the OMAP is 500MHz at OPP3 
(if I remember correctly)- how is the higher clock rate achieved?  Does 
the DSP core automatically follow (ie, does an increase in ARM freq 
automatically increase the DSP clock)?

Thanks,
Rick


G'day Rick,

TI document SPRS507B (can get it here:
http://focus.ti.com/lit/ds/symlink/omap3530.pdf) suggests recommended
Operating conditions for the OMAP chip. You'll want section 3.3,
specifically.

In a nutshell, however, the FE part will suffer significant silicon
degradation if you attempt to run 'hot' in extreme temperatures.
You could theoretically counter this with a heat exchange mechanism.  

DSP clock tracks ARM clock, far as I recall.  

If you'd like to try bumping your clock up a bit, you can set the
'mpurate' variable in uboot.

e.g. @ the uboot prompt. 
#setenv mpurate 600
#saveenv
#boot

Then once you're logged into the kernel:  
root@...:~# cat /proc/cpuinfo 
Hardware        : Gumstix Overo
Revision        : 0020
Serial          : 0000000000000000
root@...:~# cat /proc/cpuinfo
Processor       : ARMv7 Processor rev 3 (v7l)
BogoMIPS        : 597.64
Features        : swp half thumb fastmult vfp edsp thumbee neon vfpv3
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x1
CPU part        : 0xc08
CPU revision    : 3

Hardware        : Gumstix Overo
Revision        : 0020
Serial          : 0000000000000000


Cheers,
Akram.