[U-Boot-Users] RE: CPM on 8250 board seems stuck.

Yuli Barcohen yuli at arabellasw.com
Wed May 19 10:06:51 CEST 2004

>>>>> Subodh Nijsure writes:

    Subodh> To debug this we wrote a routine to enable the RISC timer on
    Subodh> the CPM.

    Subodh> We verify it that this timer is actually getting counted
    Subodh> down. This tells us that CPM is running.

    Subodh> However in the file cpm/mpc8260/serial_scc.c as soon as
    Subodh> following line of code is executed

    Subodh> tbdf-> cdb_sc |= BD_SC_READY;

    Subodh> the RISC timers stops counting.

This in many cases points to SDMA bus error. Please check SDSR.

    Subodh> So somehow it appears that the transmit buffer descriptor
    Subodh> that we are setting up for CPM to transmit data on SCC1
    Subodh> appears to be "invalid"?

Probably not the BD but the data to be sent. Check the data pointer in
the BD.

    Subodh> The CPM-RAM address that can be used is defined in
    Subodh> include/asm-ppc/cpm_8260.h (definition of CPM_DATAONLY_BASE)
    Subodh> so we moved its location around to 0x3000, also changing
    Subodh> CPM_DATA_ONLY_SIZE also, but it had no effect.

I've got 8250-based board on my desk and it works OK with default U-Boot
values. I don't think there is any difference in DPRAM map between 8260
and 8250.

    Subodh> I am sending question to folks at Motorola but if someone
    Subodh> has encountered this before, please do let me know what
    Subodh> could be the possible reason, that CPM gets stuck momemnt we
    Subodh> mark tx descriptor is valid. Since the CPM at this point
    Subodh> processing the RISC timer, I think CPM is getting the
    Subodh> clocked correctly...

 Yuli Barcohen       | Phone +972-9-765-1788 |  Software Project Leader
 yuli at arabellasw.com | Fax   +972-9-765-7494 | Arabella Software, Israel

More information about the U-Boot mailing list