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SubjectRe: pch_uart and pch_phub clock selection

2012年2月17日16:28 Feng Tang <>:
> I see that the the CM-iTC board is special-cased to set a 192MHz uart_clock.
> This is done in pch_uart.c code, but there is some register manipulation done in
> the pch_phub.c driver and I don't understand the connection. How are the two
> related?
According to your use, need to configure clock registers which are in pch_phub .
Upstreamed version, UART_CLK can be used directly(neither multiple nor
division) as UART clock.

You can get clock configuration information from SourceForge.
and extract pch_phub. you can find readme.)
I extract it and show below.


1. Over 115K baud rate UART settings
By default, UART can communicate less than 115Kbps.
In case you want UART to work more than 115Kbps, the following
clock configuration is necessary.
- Clock setting
Set BAUDSEL = usb_48mhz
Set PLL2VCO = "x 8" the clock
Set BAUDDIV = "x 1/6" the clock
Set UARTCLKSEL = PLL2 output
For details, please refer to ML7213/ML7223 EDS "5 Chip Configuration"

In case we want UART to work high baud rate(e.g.4Mbps), we set like above.
and execute "setserial /dev/ttyPCH0 baud_base 4000000".
I can see PCH_UART with 4Mbps works well.

Darren, is this answer for your question ?

> Tomoya, do you know if we can also set it to 192MHz for ML7223 IOH Bus-m/n?
Yes, you can.

ROHM Co., Ltd.

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