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| author | Dan Williams <dan.j.williams@intel.com> | 2022-04-13 01:36:17 -0600 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2022-04-28 14:01:54 -0700 |
| commit | 241d26bc26add2e2867c546f7474902406d37c60 (patch) | |
| tree | f30db393acfd7adf289c5b2d22abfc277276c232 /include/linux/acpi.h | |
| parent | cc10eee95204579fcd66fd5965073fdcbf629676 (diff) | |
| download | linux-241d26bc26add2e2867c546f7474902406d37c60.tar.bz2 | |
PCI/ACPI: Prefer CXL _OSC instead of PCIe _OSC for CXL host bridges
OB In preparation for negotiating OS control of CXL _OSC features, do the
minimal enabling to use CXL _OSC to handle the base PCIe feature
negotiation. Recall that CXL _OSC is a super-set of PCIe _OSC and the
CXL 2.0 specification mandates: "If a CXL Host Bridge device exposes CXL
_OSC, CXL aware OSPM shall evaluate CXL _OSC and not evaluate PCIe
_OSC."
Rather than pass a boolean flag alongside @root to all the helper
functions that need to consider PCIe specifics, add is_pcie() and
is_cxl() helper functions to check the flavor of @root. This also
allows for dynamic fallback to PCIe _OSC in cases where an attempt to
use CXL _OXC fails. This can happen on CXL 1.1 platforms that publish
ACPI0016 devices to indicate CXL host bridges, but do not publish the
optional CXL _OSC method. CXL _OSC is mandatory for CXL 2.0 hosts.
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Robert Moore <robert.moore@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Link: https://lore.kernel.org/r/20220413073618.291335-3-vishal.l.verma@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'include/linux/acpi.h')
| -rw-r--r-- | include/linux/acpi.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 04e5a038dd57..82d91d9ccce5 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -550,6 +550,10 @@ struct acpi_osc_context { acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context); +/* Number of _OSC capability DWORDS depends on bridge type */ +#define OSC_PCI_CAPABILITY_DWORDS 3 +#define OSC_CXL_CAPABILITY_DWORDS 5 + /* Indexes into _OSC Capabilities Buffer (DWORDs 2 & 3 are device-specific) */ #define OSC_QUERY_DWORD 0 /* DWORD 1 */ #define OSC_SUPPORT_DWORD 1 /* DWORD 2 */ |