[PATCH v5 3/4] PCI: endpoint: Add support for DOE initialization and setup in EPC core

[Manivannan Sadhasivam]

On Fri, Jun 12, 2026 at 01:54:13PM +0530, Aksh Garg wrote:
> 
> 
> On 12/06/26 00:42, Bjorn Helgaas wrote:
> > On Wed, Jun 10, 2026 at 03:32:55PM +0530, Aksh Garg wrote:
> > > Add pci_epc_init_capabilities() in EPC core driver to initialize and
> > > setup the capabilities supported by the EPC driver. This calls
> > > pci_epc_doe_setup() to setup the DOE framework for an endpoint controller,
> > > which discovers the DOE capabilities (extended capability ID 0x2E), and
> > > registers each discovered DOE mailbox for all the functions in the
> > > endpoint controller.
> > > 
> > > Add pci_epc_deinit_capabilities() in EPC core driver for cleanup of the
> > > resources used by the capabilities of the EPC driver. This calls
> > > pci_ep_doe_destroy() to destroy all DOE mailboxes and free associated
> > > resources.
> > > 
> > > Co-developed-by: Siddharth Vadapalli <s-vadapalli at ti.com>
> > > Signed-off-by: Siddharth Vadapalli <s-vadapalli at ti.com>
> > > Signed-off-by: Aksh Garg <a-garg7 at ti.com>
> > > ---
> > > +/**
> > > + * pci_epc_doe_setup() - Discover and setup DOE mailboxes for all functions
> > > + * @epc: the EPC device on which DOE mailboxes has to be setup
> > > + *
> > > + * Discover DOE (Data Object Exchange) capabilities for all physical functions
> > > + * in the endpoint controller and register DOE mailboxes.
> > > + *
> > > + * Returns: 0 on success, -errno on failure
> > > + */
> > > +static int pci_epc_doe_setup(struct pci_epc *epc)
> > > +{
> > > +	u8 func_no, vfunc_no = 0;
> > > +	u16 cap_offset;
> > > +	int ret;
> > > +
> > > +	if (!epc->ops || !epc->ops->find_ext_capability)
> > > +		return -EINVAL;
> > 
> 
> Hi Bjorn,
> 
> Thank you for your feedback comments. I will work on them and post v6
> series incorporating the changes.
> 
> > I don't see anything that sets pci_epc_ops.find_ext_capability in this
> > series, so this looks currently unused and untestable, so likely not
> > mergeable as-is.  What's the plan for users of this?
> > 
> 
> Currently there is no EPC driver upstream which supports DOE yet. However, I
> am working on a platform which supports DOE (support for
> which would be added soon). Mani pointed out that if EPC driver support
> for the same is guaranteed to be added soon, the APIs can be merged
> first.
> 
> For the demonstration purpose, he asked to show how an EPC driver is
> expected to use the API as a snippet in the cover letter itself.
> 

I retract my previous comment here. Let's not introduce dead code in the kernel.
We can review the series now, but cannot merge it until the EPC driver gets
submitted.

- Mani

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