Re: O2 RM7000 Issues

["Gleb O. Raiko" <raiko@niisi.msk.ru>]

Ralf,

Considering RM7k the latest kernel improperly sets some hazards. At 
least, mtc0_tlbw_hazard and tlbw_use_hazard shall contain 4 nops, not 2.
Also, there shall be 10 nops after modification of the K0 field of the 
config register. The suspicious place I see is in 
arch/mips/mm/c-r4k.c:coherency_setup():
        change_c0_config(CONF_CM_CMASK, CONF_CM_DEFAULT);

If the K0 field has the value different than CONF_CM_DEFAULT, we 
definitely need nops here and, I'm afraid, even the line shall be 
executed uncached.
Strictly speaking, manual doesn't clearly define the term 
"modification". I expect, if I write the same value in the K0 field, it 
doesn't consider "modification".
And I guess all boards with RM7k select DMA_NONCOHERENT. Otherwise, 
CONF_CM_DEFAULT will have a garbage in case of RM7k. Perhaps, it's worth
to select DMA_NONCOHERENT inside the "config CPU_RM7000" block.

Regards,
Gleb.