Hello, Dustin Harrison wrote: > I also run a MIPS platform and have seen this problem in 2.6.22. It > stems from the Sil3512 (and possibly others) not allowing read > access to the taskfile registers while a DMA transfer is active. > What happens for me is that when DMA_ENABLE is true the Sil3512 (in > my case) will disallow reads to the taskfile registers. So any > event that triggers a port freeze during an interrupt while DMA is > active causes a bus error to be thrown when the ata_check_status > call fires. Thanks a lot for diagnosing the problem. > I cannot reproduce this on x86. I assume it handles the taskfile > read error differently. I think we just get 0xff on IO read errors. > As a workaround I have used this patch on sata_sil.c to cover up the > problem and stop the kernel panics. But I don't think this is the > best approach. > > --- drivers/ata/sata_sil.c.orig 2009-04-01 18:15:55.000000000 -0700 > +++ drivers/ata/sata_sil.c 2009-04-03 10:51:56.000000000 -0700 > @@ -454,6 +454,23 @@ > err_hsm: > qc->err_mask |= AC_ERR_HSM; > freeze: > + > + /* Before we do a port freeze we need to ensure DMA_ENABLE is off. > + * This is because the controller will not give us access to the > taskfile > + * registers while a DMA is in progress and ata_qc_complete is > the first > + * function executed in ata_port_freeze. ata_port_freeze will > attempt to > + * access the tf registers and give us a host bus error kernel > panic. > + * > + * This code is repeated from ata_bmdma_stop because we may not > have a > + * valid qc to pass to ata_bmdma_stop. > + */ > + iowrite8(ioread8(ap->ioaddr.bmdma_addr) & ~SIL_DMA_ENABLE, > ap->ioaddr.bmdma_addr); > + > + /* According to ata_bmdma_stop, an HDMA transition requires on > PIO cycle. > + * But we can't read a taskfile register. > + */ > + ioread8(ap->ioaddr.bmdma_addr) > + > ata_port_freeze(ap); Can you please move the logic to sil_freeze() and see whether it works? The freeze handler is supposed to put the controller into idle (or at least not-crazy) state, so things like this fit there. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
