Hi,
I just ran into a problem resulting from patch 6e18b3a48ee4
("mc13xxx: Define maximum SPI clock frequency global to driver").
On a kindle2 board the SPI communication between an iMX31 and a MC13783
won't work at 20MHz. Unfortunately both ICs are BGA mounted blocking any
access with scope probes. Attempts to tweak the pad properties to
PAD_CTL_DRV_HIGH | PAD_CTL_SRE_FAST | PAD_CTL_100K_PU
did not solve the problem - anyway this is a battery powered device where
the original implementers took great care on long battery life,
e.g. PAD_CTL_DRV_HIGH should not be nessesary for PMIC control.
I do not see any way to override the 20MHz bitrate from board code, and
since the PMIC access is not time critical on an ebook-reader my choice
would be rather 200kHz.
Is there any way to override the driver supplied default max_speed_hz?
If not, my proposal is to either
* revert this patch and let the board code choose frequency
or
* reduce the speed to some common acceptable rate, e.g. 6MHz are fine
How was this solved with other SPI devices?
Cheers, Alexander
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