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parisc/pci: Switch LBA PCI bus from Hard Fail to Soft Fail mode 

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 <carlojpisani@gmail.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Reviewed-by: Grant Grundler <grantgrundler@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Helge Deller 2018-03-25 14:04:22 +02:00
parent d5654e156b
commit b845f66f78
1 changed files with 19 additions and 1 deletions
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20
drivers/parisc/lba_pci.c
View File

@ -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