On Mon, 18 Jul 2011 22:39:01 -0700 Daniel Ng2 <daniel.ng1...@gmail.com> wrote:
> > Our USB Device Controller (UDC) driver seems to get stuck in a loop waiting > for the CPM Command Register to indicate that the CPM has finished executing > a command. (It should do this by setting the cpmcr 'Command Done' bit). > > This only happens if I disable the 'Early Debug' Kernel Hacking .config > parameter. If Early Debug is enabled, then the problem goes away. > > I've narrowed it down to this line in udbg_init_cpm(void): > > setbat(1, 0xf0000000, 0xf0000000, 0x40000, PAGE_KERNEL_NCG); > > -without this line, the driver gets stuck in the loop. > > Can anyone suggest why? Is your USB driver accessing effective addresses from 0xf0000000 to 0xf0040000? It should be using ioremap(). > Also, what undesireable effects might there be of keeping the above call to > setbat()? It's squatting on a chunk of virtual address space without properly reserving it. This is bad enough for a debug hack (and should be fixed). Don't extend it to normal operation -- especially not as a substitute for understanding the root cause of your problem. -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
