| Date | Wed, 31 Aug 2022 12:00:27 +0100 | From | Jonathan Cameron <> | Subject | Re: [PATCH 09/15] cxl/acpi: Determine PCI host bridge's ACPI UID |
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On Wed, 31 Aug 2022 10:15:57 +0200 Robert Richter <rrichter@amd.com> wrote:
> The UID is needed to read the RCH's CEDT entry with the RCRB base > address. Determine the host's UID from its ACPI fw node. > > Signed-off-by: Robert Richter <rrichter@amd.com> > --- > drivers/cxl/acpi.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c > index f9cdf23a91a8..b3146b7ae922 100644 > --- a/drivers/cxl/acpi.c > +++ b/drivers/cxl/acpi.c > @@ -368,8 +368,20 @@ struct pci_host_bridge *cxl_find_next_rch(struct pci_host_bridge *host) > static int __init cxl_restricted_host_probe(struct platform_device *pdev) > { > struct pci_host_bridge *host = NULL; > + struct acpi_device *adev; > + unsigned long long uid = ~0; > > while ((host = cxl_find_next_rch(host)) != NULL) { > + adev = ACPI_COMPANION(&host->dev); > + if (!adev || !adev->pnp.unique_id || > + (kstrtoull(adev->pnp.unique_id, 10, &uid) < 0))
There is an acpi_device_uid() accessor function that should probably be used here.
Also, should a fialure to convert to an integer (or one within limits) be something we paper over? Feels like we should fail hard if that happens.
Admittedly I can't immediately find any spec that states that the _UID should be either integer or under 32 bits... ACPI allows a string and CXL just says it's 4 bytes long.
> + continue; > + > + dev_dbg(&adev->dev, "host uid: %llu\n", uid); > + > + if (uid > U32_MAX) > + continue; > + > dev_info(&host->dev, "host supports CXL\n"); > } >
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