Hi,
On Thursday 12 July 2012 09:38 AM, Prashant Gaikwad wrote:
On Wednesday 11 July 2012 07:33 PM, Rob Herring wrote:
On 07/11/2012 07:56 AM, Prashant Gaikwad wrote:
Hi,
I am working on DT binding for Tegra DVFS.
<snip>
compatible = "nvidia,tegra30-dvfs-table";
reg_id =<&sm0>;
#address-cells =<1>;
#size-cells =<0>;
voltage-array =<750 775 800 825 850 875 900 925 950 975
1000 1025 1050 1100 1125>;
The SOC is really characterized at all these voltages?
Not really, but different processes of single SoC are characterized
for different voltages and this array covers all those voltages.
};
device {
dvfs =<&cpu-dvfs-table>;
frequency-table@102 {
reg =<0x102>;
frequencies =<314 314 314 456 456 456 608 608
608
760 817 817 912 1000>;
I don't see the point of repeating frequencies.
};
frequency-table@002 {
reg =<0x002>;
frequencies =<598 598 750 750 893 893 1000>;
};
How do you determine the voltage for a frequency on table 2?
I'd expect a single property with freq/volt pairs or 2 properties for
freq and voltage where there is a 1:1 relationship (freq N uses
voltage N).
How this will work:
voltage-array =<750 775 800 825 850 875 900 925 950 975 1000 1025
1050 1100 1125>
frequencies-1 =<314 314 314 456 456 456 608 608 608 760 817 817
912 1000>;
frequencies-2 =<598 598 750 750 893 893 1000>;
Freq and voltage has 1:1 relationship but as single voltage table is
used for different processes we have more entries in voltage table
than freq table.
Frequency table 1 is mapped till 1100mV while frequency table 2 is
mapped till 900mV only, it maintains 1:1 relationship.
About repeating frequencies, operating voltage for a frequency would
be the highest one mapped in the table.
For example, in frequency table 2 operating voltage for 750MHz would
be 825mV while for 893MHz it would be 875mV. Unmapped entries could be
replaced with 0 to make reading better.
Advantage it provides is single voltage table used for multiple
frequency tables, as can be observed from above tables, operating
voltage for 314MHz in freq table 1 is 800mV while there is no
frequency in table 2 at that voltage.
I know this makes reading difficult but it provides flexibility,
I hope it explains the implementation.
Does this explanation help?
Regards,
Prashant G
Rob
};
Thanks& Regards,
Prashant G
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
--
To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
