On 11/23/2010 07:44 AM, Gary Thomas wrote:
On 11/22/2010 01:26 PM, Benjamin Herrenschmidt wrote:
On Mon, 2010-11-22 at 03:01 -0700, Gary Thomas wrote:
I have a bit more information on this. I'm pretty sure that the failures
are only happening in my SCSI (SATA actually) code. My board (8347ea)
has
a PCI bus with a SIL SATA controller. This combo works perfectly in
2.6.28.
In 2.6.32, it will run for a while (possibly quite a while), then
timeout
trying to do a large block write - typically 256 blocks. Once this
timeout
happens, the SIL controller is stuck and accesses to it will eventually
cause the whole system to hang (as above).
Was there any major change in how PCI or DMA was handled between 2.6.28
and 2.6.32? Given the ephemeral nature of these failures (multiple runs
all eventually fail, but never the same twice), my only hope of
fixing it
will be to have some ideas what might have changed.
Maybe the changes you did to the PCI outbound windows are now breaking
DMA ? Make sure the outbound and inbound don't overlap for example and
that all RAM is reachable for inbound.
Here's what I did to work around this - in my DTS, I set up my PCI as
ranges = <0x02000000 0x0 0xC4000000 0xC4000000 0x0 0x1C000000
0x01000000 0x0 0x00000000 0xB8000000 0x0 0x00100000>;
Before, I had it as
ranges = <0x02000000 0x0 0xC0000000 0xC0000000 0x0 0x20000000
0x01000000 0x0 0x00000000 0xB8000000 0x0 0x00100000>;
I wasn't sure how to reserve the memory (based on your earlier suggestion),
so I just narrowed the window. Note that I did not change the PCI hardware
registers (maybe the FSL code does?), so the outbound window should still
be the whole 512MB.
If this isn't viable, perhaps you could explain a bit more how to reserve
such a chunk of memory so that the PCI mappings remain the same.
Any ideas on this? I'm a bit lost as to how to reserve the memory like
you suggested and what I've tried so far has met little success.
Thanks again
--
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Gary Thomas | Consulting for the
MLB Associates | Embedded world
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