On 2023/7/26 04:59, Bjorn Helgaas wrote:

On Mon, Jul 24, 2023 at 10:18:07AM +0100, Jonathan Cameron wrote:

quoted

On Mon, 24 Jul 2023 10:34:08 +0800
Shuai Xue [off-list ref] wrote:

quoted

On 2023/7/10 20:04, Shuai Xue wrote:

quoted

On 2023/6/16 16:39, Shuai Xue wrote:  

quoted

On 2023/6/6 15:49, Shuai Xue wrote:  

quoted

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This patchset adds the PCIe Performance Monitoring Unit (PMU) driver support
for T-Head Yitian 710 SoC chip. Yitian 710 is based on the Synopsys PCI Express
Core controller IP which provides statistics feature.

quoted

...
Really a question for Bjorn I think, but here is my 2 cents...

The problem here is that we need to do that fundamental redesign of the
way the PCI ports drivers work.  I'm not sure there is a path to merging
this until that is done.  The bigger problem is that I'm not sure anyone
is actively looking at that yet.  I'd like to look at this (as I have
the same problem for some other drivers), but it is behind various
other things on my todo list.

Bjorn might be persuaded on a temporary solution, but that would come
with some maintenance problems, particularly when we try to do it
'right' in the future.  Maybe adding another service driver would be
a stop gap as long as we know we won't keep doing so for ever. Not sure.

I think the question here is around the for_each_pci_dev() in
__dwc_pcie_pmu_probe()?  I don't *like* that because of the
assumptions it breaks (autoload doesn't work, hotplug doesn't work),
but:

  - There are several other drivers that also do this,
  - I don't have a better suggest for any of them,
  - It's not a drivers/pci thing, so not really up to me anyway,

so I don't have any problem with this being merged as-is, as long as
you can live with the limitations.

I don't think this series does anything to work around those
limitations, i.e., it doesn't make up fake device IDs for module
loading or fake events for hotplug, so it seems like we could improve
the implementation later if we ever have a way to do it.

Bjorn

+ Will

Ok, thank you for confirmation, Bjorn. Then it comes to perf driver parts and
it is really a question for @Will I think.

What's your opinion about merging this patch set, @Will?

Best Regards,
Shuai


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