Carlo Pisani noticed that his C3600 workstation behaved unstable during heavy I/O on the PCI bus with a VIA VT6421 IDE/SATA PCI card. To avoid such instability, this patch switches the LBA PCI bus from Hard Fail mode into Soft Fail mode. In this mode the bus will return -1UL for timed out MMIO transactions, which is exactly how the x86 (and most other architectures) PCI busses behave. This patch based on a proposal by Grant Grundler and Kyle McMartin 10 years ago: https://www.spinics.net/lists/linux-parisc/msg01027.html Cc: Carlo Pisani <carlojpisani@xxxxxxxxx> Cc: Kyle McMartin <kyle@xxxxxxxxxxx> Cc: Grant Grundler <grantgrundler@xxxxxxxxx> Signed-off-by: Helge Deller <deller@xxxxxx> diff --git a/drivers/parisc/lba_pci.c b/drivers/parisc/lba_pci.c index 41b740aed3a3..69bd98421eb1 100644 --- a/drivers/parisc/lba_pci.c +++ b/drivers/parisc/lba_pci.c @@ -1403,9 +1403,27 @@ lba_hw_init(struct lba_device *d) WRITE_REG32(stat, d->hba.base_addr + LBA_ERROR_CONFIG); } - /* Set HF mode as the default (vs. -1 mode). */ + + /* + * Hard Fail vs. Soft Fail on PCI "Master Abort". + * + * "Master Abort" means the MMIO transaction timed out - usually due to + * the device not responding to an MMIO read. We would like HF to be + * enabled to find driver problems, though it means the system will + * crash with a HPMC. + * + * In SoftFail mode "~0L" is returned as a result of a timeout on the + * pci bus. This is like how PCI busses on x86 and most other + * architectures behave. In order to increase compatibility with + * existing (x86) PCI hardware and existing Linux drivers we enable + * Soft Faul mode on PA-RISC now too. + */ stat = READ_REG32(d->hba.base_addr + LBA_STAT_CTL); +#if defined(ENABLE_HARDFAIL) WRITE_REG32(stat | HF_ENABLE, d->hba.base_addr + LBA_STAT_CTL); +#else + WRITE_REG32(stat & ~HF_ENABLE, d->hba.base_addr + LBA_STAT_CTL); +#endif /* ** Writing a zero to STAT_CTL.rf (bit 0) will clear reset signal -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
