Re: [PATCH v11 05/12] cxl: Cache endpoint decoder settings during PCI enumeration

[Srirangan Madhavan]

On 9/9/26 7:21 PM, Li Ming wrote:
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>
>
> 在 2026/9/10 08:07, Srirangan Madhavan 写道:
> > On 9/2/26 7:03 AM, Li Ming wrote:
> > > > +             return true;
> > > > +
> > > > +     pci_cxl_hdm_init(pdev);
> > >
> > > I forgot to ask a question in v10, sorry about that.
> > >
> > > I am wondering why calling pci_cxl_hdm_init() in
> > > cxl_pci_hdm_decoder_count_match() is needed. pci_bus_add_device()
> > > already does pci_cxl_hdm_init(), so if my understanding is correct,
> > > pdev->hdm is not NULL here, so this pci_cxl_hdm_init() here will not do
> > > anything except checking if pdev->hdm is NULL. I am not sure if I miss
> > > some cases for that.
> >
> > Hi Li Ming!
> > Your question is valid. pci_bus_add_device() is the normal
> > initialization path. The later call is a retry for cases where that
> > attempt did not publish pdev->hdm, for example because allocation or
> > MMIO mapping failed at that point.
> > If initialization succeeded earlier, the existing cache is detected
> > and the retry returns without rebuilding it. I clarified this behavior
> > in the v12 commit message.
> Hi Srirangan,
>
>
> Thanks for your explaination.
>
> I think removing this retry should be better if it is only used for the
> case that allocation or MMIO mapping failure during
> pci_bus_add_device(). Because these failures are not expected to happen
> often, and removing it can make pci_cxl_hdm_init() implementation
> simpler. If only pci_bus_add_device() calls pci_cxl_hdm_init(), you
> won't have to hold cxl_rwsem.dpa and check whether pdev->hdm is NULL in
> __pci_cxl_hdm_init(). Besides, hold cxl_rwsem.dpa lock in
> pci_cxl_hdm_release() is not needed, because the function is called in
> pci_release_dev() where is at the end of this pci device's lifecycle.
>
>
> Ming

Hi Ming!

In v12 I removed the retry from the CXL core path and kept 
pci_cxl_hdm_init() only in pci_bus_add_device().
--
Regards,
Srirangan