Re: [PATCH v6 4/4] thermal: k3_j72xx_bandgap: Add the bandgap driver support
From: Daniel Lezcano
Date: Tue May 10 2022 - 11:29:18 EST
On 09/05/2022 05:10, J, KEERTHY wrote:
On 4/27/2022 12:16 PM, Keerthy wrote:
Add VTM thermal support. In the Voltage Thermal Management
Module(VTM), K3 J72XX supplies a voltage reference and a temperature
sensor feature that are gathered in the band gap voltage and
temperature sensor (VBGAPTS) module. The band gap provides current and
voltage reference for its internal circuits and other analog IP
blocks. The analog-to-digital converter (ADC) produces an output value
that is proportional to the silicon temperature.
Currently reading temperatures only is supported. There are no
active/passive cooling agent supported.
J721e SoCs have errata i2128: https://www.ti.com/lit/pdf/sprz455
The VTM Temperature Monitors (TEMPSENSORs) are trimmed during production,
with the resulting values stored in software-readable registers. Software
should use these register values when translating the Temperature
Monitor output codes to temperature values.
It has an involved workaround. Software needs to read the error codes for
-40C, 30C, 125C from the efuse for each device & derive a new look up
table
for adc to temperature conversion. Involved calculating slopes &
constants
using 3 different straight line equations with adc refernce codes as the
y-axis & error codes in the x-axis.
-40C to 30C
30C to 125C
125C to 150C
With the above 2 line equations we derive the full look-up table to
workaround the errata i2128 for j721e SoC.
Hi Daniel,
Any feedback on this series? Let me know.
There are a few but that would be nit picking and I don't want to
postpone this driver any longer.
How do you want to proceed? Shall I take it through my tree?
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