Mark Lord wrote:
This patch is for trial/critique use only at the moment.
Once I hear back from a few people who actually use it,
I'll post an updated fix for upstream/backstream inclusion.
I spent this afternoon nitpicking and bitpicking through the interrupt
code
in sata_mv.c, and I believe I found a race on the hc_irq_cause
register. The
code was "helpfully" attempting to use read-modify-write to clear
individual
port bits there, but this is impossible to do in a race-free fashion.
So.. the obvious fix is to just write the bits being cleared, without
touching
anything else. This will also be faster, too, since no read is
required or
desired. I really don't see a downside, as long as it actually works
for everyone.
It does work for me here.
I tried the patch and it works as well as it did without the patch. That
is to say, timeouts still happen, every couple of minutes on moderate
read/write load. Patched driver has not seen much use here as the system
is in production use and it becomes quickly frustrating to wait for
something to happen.
I also tried removing ATA_PROT_NODATA from libata-sff.c, as mentioned
earlier, but after that all disks timeout constantly. It also dropped
all sata_mv connected disks from md array immediately on boot.
I still see timeouts only on 4 lower ports where disk has also been
connected to port +4. i.e. if port 7 is empty, port 3 will work just
fine. I just would like to see some confirmation that others are seeing
this same kind of behavior.
Hardware: Supermicro aoc-sat2-mv8 controller (6081 chip) and WD7500AYYS
drives.
--
Harri.
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