4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Helge Deller <del...@gmx.de> [ Upstream commit b845f66f78bf42a4ce98e5cfe0e94fab41dd0742 ] 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 is 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 <carlojpis...@gmail.com> Cc: Kyle McMartin <k...@mcmartin.ca> Reviewed-by: Grant Grundler <grantgrund...@gmail.com> Signed-off-by: Helge Deller <del...@gmx.de> Signed-off-by: Sasha Levin <alexander.le...@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/parisc/lba_pci.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) --- a/drivers/parisc/lba_pci.c +++ b/drivers/parisc/lba_pci.c @@ -1365,9 +1365,27 @@ 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
