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Daniel Golle 5a1e4a7fdb oxnas: reduce size of ATA DMA descriptor space ... After years of trying to find the reason for random kernel crashes while both CPU and SATA are under load it has been found. Some odd commented-out #defines in kref's single-port driver [1] which were copied from the vendor driver made me develop a theory: The IO-mapped memory area for DMA descriptors apparetly got some holes just before the alignment boundaries. This feels like an off-by-one bug in the hardware or maybe those fields are used internally by the SATA controller's firmware. Whatever the cause is: they cannot be used and trying to use them results in reading back unexpected stuff and ends up with oopsing Unable to handle kernel paging request at virtual address d085c004 Work around the issue by reducing the area used for bmdma descriptors. This reduces SATA performance (iops) quite a bit, but finally makes things work reliably. Possibly one could optimize this much more by really just skipping the holes in that memory area -- however, that seems to be non-trivial with the driver and libata in it's current form (suggestions are welcome). The 'proper' way to have good SATA performance would be to make use of the hardware RAID features (one can use the JBOD mode to access even just a single disc transparently through the RAID controller integrated in the SATA host instead of accessing the SATA ports 'raw' as we do now). [1]: https://github.com/kref/linux-oxnas/blob/master/drivers/ata/sata_oxnas.c#L25 Signed-off-by: Daniel Golle <daniel@makrotopia.org> (cherry picked from commit 5793112f751ee3d9f841af4846d68e6b1ff1bff4, including fixup commit d75e75306301852a848824cf268d8b58eda28a8a)		4 years ago
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ata	oxnas: reduce size of ATA DMA descriptor space	4 years ago
pci/host	oxnas: move PCIe controller outside of simple-bus	6 years ago
phy	oxnas: pcie: model shared resource as external pcie-phy driver	6 years ago
power/reset	oxnas: replace oxnas-restart with version to be submitted to upstream	6 years ago
usb/host	oxnas: bring in new oxnas target	6 years ago