Just poking this thread to make sure it's not dead. :)
I tested Yijing's proposal and it is successful on our Intel server
platforms; hoping either this or something that derives similar behavior
will be applied so we can remove bus tuning kernel parameters.
Tested-by: Keith Busch <keith.busch@xxxxxxxxx>
On Thu, 4 Sep 2014, Yijing Wang wrote:
if (pcie_bus_config == PCIE_BUS_TUNE_OFF) {
+ pcie_bus_update_set(dev);
You're only adding this to the PCIE_BUS_TUNE_OFF path. Can't the same
problem occur for other pcie_bus_config settings?
We only found the problem during PCIE_BUS_TUNE_OFF set. Other mode like PCIE_BUS_SAFE and PCIE_BUS_PEER2PEER.
This issue won't happen.
Sorry, I can't parse this. Are you saying the problem won't happen in
the other modes? Why not?
Hi Bjorn, when in PCIE_BUS_SAFE mode, pcie_find_smpss() will find the largest available mpss in a pcie path.
Then call pcie_bus_configure_set() to set all devices' mps to the largest available mps in this path, so
all devices in the path will have the same mps. When in PCIE_BUS_PEER2PEER, all devices' mps will be set to 128B
for safety. And to the PCIE_BUS_PERFORMANCE mode, I found Jon's comment in pcie_write_mps(),
/* For "Performance", the assumption is made that
* downstream communication will never be larger than
* the MRRS. So, the MPS only needs to be configured
* for the upstream communication. This being the case, <------
* walk from the top down and set the MPS of the child
* to that of the parent bus.
So I think the problem won't happen in other modes.
Thanks!
Yijing.
pcie_bus_detect_mps(dev);
return 0;
}
.
--
Thanks!
Yijing
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