Up until now cpu clock gets initialized at 384 MHz, which is
the highest supported cpu clock.
Recent A20 batches show an increased percentage of modules
reacting very sensitive to operating conditions outside the
specifications.
The cpu dies very shortly after PLLs, core frequency or cpu
voltage are missconfigured. E.g.:
- uboot SPL selects 384 MHz as cpu clock which requires a cpu
voltage of at least 1.1 V.
- Linux CPU Frequency scaling with most sun7i dts will reduce
cpu voltage down to 1.0 V.
- When intiating a reboot or reset from linux the cpu voltage
may keep the 1.0 V configuration and the cpu dies during SPL
initialization.
Therefore reduce cpu clock at uboot SPL initialization down
to 144 MHz from 384 MHz.
Use patch until KConfig option in uboot becomes available.
Signed-off-by: Ludwig Kormann <ludwig.kormann@ict42.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
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