cpm_uart_console_write() stuck in waiting for transmitter fifo ready

Scott Wood scottwood at freescale.com
Sat Jul 17 04:13:33 EST 2010

On Fri, 16 Jul 2010 00:12:21 -0700
Shawn Jin <shawnxjin at gmail.com> wrote:

> >> Why would the TxBD be filled with all 0xF? Would it be possible that
> >> the bdbase actually points somewhere else other than the TxBD?
> >
> > The virtual address 0xfddfa000 is mapped to 0xfa202000. I suspect that
> > the TxBD of my MPC870 may not start at 0xfa202020.
> >
> > I notice that for adder875, ep88xc and mpc885ads, the muram data's reg
> > = <0 0x1c00> but for mgsuvd, its reg = <0x800 0x1800>. How does the
> > kernel use muram for 885 family SoCs? How much muram should be
> > reserved for data?
> >
> > My RCCR=0x1, meaning the first 512B is for microcode. So the data and
> > the TxBD should really be starting at 0xfa202200? Then my muram data's
> > reg should be <0x200 ?>? What size shall I specify?
> After the muram data's reg is changed to <0x200 0x1a00>, the cpm_uart
> driver works properly and the kernel messages are printed on the
> serial port.

The muram node is supposed to show the portions of DPRAM that are
usable by the OS.  If some portion has been taken up by microcode (or
anything else not under the OS's control) before the OS has started,
then it must be excluded from the muram node.


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