Hi,
On 9/11/20 1:13 PM, Pete Batard wrote:
It might be worth sourcing public documentation, if you have any,
indicating where these numeric values ultimately come from (the offset
for absolute zero is easy to figure out, but the rest, not so much).
I'm only privy to things that can be found with a google search.
So at the moment I'm not aware of proper first party documentation on
the thermal sensor.
So
https://elixir.bootlin.com/linux/v5.9-rc4/source/arch/arm/boot/dts/bcm2711.dtsi#L413
gives us the base+slope values (410040, 487). Given the linux the units
are in 1/1000h C, the remainder of the calculation is to adjust to 1/10th K.
There is also
https://www.raspberrypi.org/documentation/hardware/raspberrypi/frequency-management.md
There is also a bit of documentation around "temp_limit"
https://www.raspberrypi.org/documentation/configuration/config-txt/overclocking.md
Which names 80-85C as the region that the cores should be throttled and
some other thermal recommendations.
Finally, various mentions of the AVS (beyond the official document
naming the int, but not the base address despite it being in the DT) in
commit messages/etc help to clarify things, but none are particularly
helpful on their own.
Apart from that:
On 2020.09.10 00:11, Jeremy Linton wrote:
The current mainline DT indicates that the thermal offset
on the rpi is 410040 rather than the 419949 being used.
This means our temp calculation is offset nearly 10C higher
when running in ACPI mode vs DT.
Signed-off-by: Jeremy Linton <jeremy.lin...@arm.com>
---
Platform/RaspberryPi/AcpiTables/Dsdt.asl | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Platform/RaspberryPi/AcpiTables/Dsdt.asl
b/Platform/RaspberryPi/AcpiTables/Dsdt.asl
index 2b9e8211cf..d116f965e1 100644
--- a/Platform/RaspberryPi/AcpiTables/Dsdt.asl
+++ b/Platform/RaspberryPi/AcpiTables/Dsdt.asl
@@ -269,7 +269,7 @@ DefinitionBlock ("Dsdt.aml", "DSDT", 5, "RPIFDN",
"RPI", 2)
Field (TEMS, DWordAcc, NoLock, Preserve) {
TMPS, 32
}
- return (((419949 - ((TMPS & 0x3ff) * 487)) / 100) + 2732);
+ return (((410040 - ((TMPS & 0x3ff) * 487)) / 100) + 2732);
}
Method (_SCP, 3) { } // receive cooling policy
from OS
Reviewed-by: Pete Batard <p...@akeo.ie>
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