Re: [PATCH] PCI: update device mps when doing pci hotplug

[Yijing Wang <wangyijing@huawei.com>]

>>>>      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