Re: [PATCH v19 01/10] PCI: endpoint: Set ID and of_node for function driver

[Frank Li <Frank.li@nxp.com>]

On Wed, Jul 02, 2025 at 08:25:17PM +0530, Manivannan Sadhasivam wrote:
> On Wed, Jul 02, 2025 at 10:40:53AM GMT, Frank Li wrote:
> > On Wed, Jul 02, 2025 at 04:30:48PM +0530, Manivannan Sadhasivam wrote:
> > > On Mon, Jun 09, 2025 at 12:34:13PM GMT, Frank Li wrote:
> > > > Set device ID as 'vfunc_no << 3 | func_no' and use
> > > > 'device_set_of_node_from_dev()' to set 'of_node' the same as the EPC parent
> > > > device.
> > > >
> > > > Currently, EPF 'of_node' is NULL, but many functions depend on 'of_node'
> > > > settings, such as DMA, IOMMU, and MSI. At present, all DMA allocation
> > > > functions use the EPC's device node, but they should use the EPF one.
> > > > For multiple function drivers, IOMMU/MSI should be different for each
> > > > function driver.
> > > >
> > >
> > > We don't define OF node for any function, so device_set_of_node_from_dev() also
> > > ends up reusing the EPC node. So how can you make use of it in multi EPF setup?
> >
> > In mfd devices, children devices reuse parent's of_node
> > drivers/gpio/gpio-adp5585.c
> > drivers/input/keyboard/adp5589-keys.c
> > drivers/pwm/pwm-adp5585.c
> >
> > multi EPF should be similar to create multi children devices of mfd.
> >
>
> No, they are not similar. MFD are real physical devices, but EPFs are (so far)
> software based entities.
>
> > > I don't understand.
> >
> > >
> > > > If multiple function devices share the same EPC device, there will be
> > > > no isolation between them. Setting the ID and 'of_node' prepares for
> > > > proper support.
> >
> > Only share the same of_node.
> >
> > Actually pci host bridge have similar situation, all pci ep devices reuse
> > bridge's of node. framework use rid to distringuish it. EPF can use device::id
> > to do similar things.
> >
> > Actually iommu face the similar problem. So far, there are not EP device enable
> > iommu yet, because it needs special mapping.
> >
> > Prevously, I consider create dymatic of_node for each EPF and copy iommu/msi
> > information to each children. But when I see adp5585 case, I think direct
> > use parent's of_node should be simple and good enough.
> >
> > In future, I suggest add children dt binding for it. For example: EPF provide
> > a mailbox interface. how other dts node to refer to this mailbox's phandle?
> >
>
> As I said above, EPFs are not real devices. There is currently only one
> exception, MHI, which is backed by a hardware entity. So we cannot add
> devicetree nodes for EPF, unless each EPF is a hardware entity.

But how resolve this problem, if a DT device need phandle to a EPF? anyway
this is off topic. let go back this doorbell.

It needs an of_node for EPF device, I tried many method before.

Create dymatic of_node for it? MSI framework still go through to parent
of_node to get such information. not big differnece as my view.

Frank

>
> - Mani
>
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