Benjamin Herrenschmidt wrote:

quoted

radeonfb_setcolreg: INPLL
radeonfb_setcolreg: OUTPLL
radeonfb_setcolreg: OUTPLL
... last three lines repeated 63 times

Hrm... the last (serie of 64 setcolreg) are probably X beeing extremely
dumb, and calling the ioctl 64 times to set each palette entry instead
of doing a single call for the whole palette...

Anyway. Except for maybe the double set-par on switch from X to console,
there isn't much more we can do here. We might be able to improve X but
there is a significant lag between a fix done to X.org HEAD appears in
any distro. The fact is, according to ATI, there is a HW bug on M6 taht
can cause lockups of the chip, and this 5ms workaround is necessary to
avoid it... 

But it's not specific to X11; I've applied the patch you posted and the
same symptoms occur for pure tty switching as well, the delay has decreased
a bit (it's hard to measure, but around a second), but it's still rather
annoying to work with.

Is it distinguishable which M6 models are buggy? I'm using my X31 for about
a year now and have probably made some tens of thousands of switches without
lockups, so presumably not all models cause lockups.

Cheers,
        Moritz