On Mon, 23 Jan 2023 11:17:00 +0100
Lukas Wunner <lukas@xxxxxxxxx> wrote:
> Currently a DOE instance cannot be shared by multiple drivers because
> each driver creates its own pci_doe_mb struct for a given DOE instance.
> For the same reason a DOE instance cannot be shared between the PCI core
> and a driver.
>
> Overcome this limitation by creating mailboxes in the PCI core on device
> enumeration. Provide a pci_find_doe_mailbox() API call to allow drivers
> to get a pci_doe_mb for a given (pci_dev, vendor, protocol) triple.
>
> On device removal, tear down mailboxes in two steps:
>
> In pci_stop_dev(), before the driver is unbound, stop ongoing DOE
> exchanges and prevent new ones from being scheduled. This ensures that
> a hot-removed device doesn't needlessly wait for a running exchange to
> time out.
Ah. I didn't have to go far to find answer to my earlier query! This
needs to be two step - hence the split in the previous patch.
>
> In pci_destroy_dev(), after the driver is unbound, free the mailboxes
> and their internal data structures.
>
> Tested-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Very nice. One comment on a possible future need inline.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> +/**
> + * pci_find_doe_mailbox() - Find Data Object Exchange mailbox
> + *
> + * @pdev: PCI device
> + * @vendor: Vendor ID
> + * @type: Data Object Type
> + *
> + * Find first DOE mailbox of a PCI device which supports the given protocol.
> + *
> + * RETURNS: Pointer to the DOE mailbox or NULL if none was found.
> + */
> +struct pci_doe_mb *pci_find_doe_mailbox(struct pci_dev *pdev, u16 vendor,
> + u8 type)
This is good for now. We may want eventually to be slightly
more flexible and allow for a 'find instance X of a DOE that supports Y'.
Can solve that when we need it though.
> +{
> + struct pci_doe_mb *doe_mb;
> + unsigned long index;
> +
> + xa_for_each(&pdev->doe_mbs, index, doe_mb)
> + if (pci_doe_supports_prot(doe_mb, vendor, type))
> + return doe_mb;
> +
> + return NULL;
> +}
> +EXPORT_SYMBOL_GPL(pci_find_doe_mailbox);
