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Message-ID: <1966378.CQOukoFCf9@rafael.j.wysocki>
Date: Mon, 22 Dec 2025 20:21:19 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux ACPI <linux-acpi@...r.kernel.org>,
Jonathan Cameron <jonathan.cameron@...wei.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Linux PCI <linux-pci@...r.kernel.org>, Bjorn Helgaas <helgaas@...nel.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
Hans de Goede <hansg@...nel.org>,
Mario Limonciello <mario.limonciello@....com>
Subject:
[PATCH v2.1 6/8] ACPI: bus: Rework the handling of \_SB._OSC platform
features
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Both acpi_bus_osc_negotiate_platform_control() and
acpi_bus_osc_negotiate_usb_control() first call acpi_run_osc() to
evaluate _OSC in "query mode", with OSC_QUERY_ENABLE set in the
capabilities buffer, and then use the resultant feature mask as
the input buffer for requesting control of those features by
calling acpi_run_osc() to evaluate _OSC with OSC_QUERY_ENABLE clear.
This involves some code duplication and unnecessary memory
allocations, so introduce a new helper function carrying out an
_OSC handshake along the lines of the above description in a simpler
way and update acpi_bus_osc_negotiate_platform_control() to use it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
v1 -> v2.1:
* Add printing error messages regarding unexpected _OSC errors when
processing a feature mask acknowledged previously (Jonathan).
* Update the changelog after moving the essential change to patch [1/8].
---
drivers/acpi/bus.c | 141 +++++++++++++++++++++++++++++++++++++----------------
1 file changed, 101 insertions(+), 40 deletions(-)
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -325,6 +325,92 @@ out:
}
EXPORT_SYMBOL(acpi_run_osc);
+static int acpi_osc_handshake(acpi_handle handle, const char *uuid_str,
+ int rev, struct acpi_buffer *cap)
+{
+ union acpi_object in_params[4], *out_obj;
+ size_t bufsize = cap->length / sizeof(u32);
+ struct acpi_object_list input;
+ struct acpi_buffer output;
+ u32 *capbuf, *retbuf, test;
+ guid_t guid;
+ int ret, i;
+
+ if (!cap || cap->length < 2 * sizeof(32) || guid_parse(uuid_str, &guid))
+ return -EINVAL;
+
+ /* First evaluate _OSC with OSC_QUERY_ENABLE set. */
+ capbuf = cap->pointer;
+ capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE;
+
+ ret = acpi_eval_osc(handle, &guid, rev, cap, in_params, &output);
+ if (ret)
+ return ret;
+
+ out_obj = output.pointer;
+ retbuf = (u32 *)out_obj->buffer.pointer;
+
+ if (acpi_osc_error_check(handle, &guid, rev, cap, retbuf)) {
+ ret = -ENODATA;
+ goto out;
+ }
+
+ /*
+ * Clear the feature bits in the capabilities buffer that have not been
+ * acknowledged and clear the return buffer.
+ */
+ for (i = OSC_QUERY_DWORD + 1, test = 0; i < bufsize; i++) {
+ capbuf[i] &= retbuf[i];
+ test |= capbuf[i];
+ retbuf[i] = 0;
+ }
+ /*
+ * If none of the feature bits have been acknowledged, there's nothing
+ * more to do. capbuf[] contains a feature mask of all zeros.
+ */
+ if (!test)
+ goto out;
+
+ retbuf[OSC_QUERY_DWORD] = 0;
+ /*
+ * Now evaluate _OSC again (directly) with OSC_QUERY_ENABLE clear and
+ * the updated input and output buffers used before. Since the feature
+ * bits that were clear in the return buffer from the previous _OSC
+ * evaluation are also clear in the capabilities buffer now, this _OSC
+ * evaluation is not expected to fail.
+ */
+ capbuf[OSC_QUERY_DWORD] = 0;
+ /* Reuse in_params[] populated by acpi_eval_osc(). */
+ input.pointer = in_params;
+ input.count = 4;
+
+ if (ACPI_FAILURE(acpi_evaluate_object(handle, "_OSC", &input, &output))) {
+ ret = -ENODATA;
+ goto out;
+ }
+
+ /*
+ * Clear the feature bits in capbuf[] that have not been acknowledged.
+ * After that, capbuf[] contains the resultant feature mask.
+ */
+ for (i = OSC_QUERY_DWORD + 1; i < bufsize; i++)
+ capbuf[i] &= retbuf[i];
+
+ if (retbuf[OSC_QUERY_DWORD] & OSC_ERROR_MASK) {
+ /*
+ * Complain about the unexpected errors and print diagnostic
+ * information related to them.
+ */
+ acpi_handle_err(handle, "_OSC: errors while processing control request\n");
+ acpi_handle_err(handle, "_OSC: some features may be missing\n");
+ acpi_osc_error_check(handle, &guid, rev, cap, retbuf);
+ }
+
+out:
+ ACPI_FREE(out_obj);
+ return ret;
+}
+
bool osc_sb_apei_support_acked;
/*
@@ -356,19 +442,16 @@ EXPORT_SYMBOL_GPL(osc_sb_native_usb4_sup
bool osc_sb_cppc2_support_acked;
-static u8 sb_uuid_str[] = "0811B06E-4A27-44F9-8D60-3CBBC22E7B48";
static void acpi_bus_osc_negotiate_platform_control(void)
{
- u32 capbuf[2], *capbuf_ret;
- struct acpi_osc_context context = {
- .uuid_str = sb_uuid_str,
- .rev = 1,
- .cap.length = 8,
- .cap.pointer = capbuf,
+ static const u8 sb_uuid_str[] = "0811B06E-4A27-44F9-8D60-3CBBC22E7B48";
+ u32 capbuf[2];
+ struct acpi_buffer cap = {
+ .pointer = capbuf,
+ .length = sizeof(capbuf),
};
acpi_handle handle;
- capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE;
capbuf[OSC_SUPPORT_DWORD] = OSC_SB_PR3_SUPPORT; /* _PR3 is in use */
if (IS_ENABLED(CONFIG_ACPI_PROCESSOR_AGGREGATOR))
capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_PAD_SUPPORT;
@@ -414,43 +497,21 @@ static void acpi_bus_osc_negotiate_platf
if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle)))
return;
- if (ACPI_FAILURE(acpi_run_osc(handle, &context)))
- return;
-
- capbuf_ret = context.ret.pointer;
- if (context.ret.length <= OSC_SUPPORT_DWORD) {
- kfree(context.ret.pointer);
+ if (acpi_osc_handshake(handle, sb_uuid_str, 1, &cap))
return;
- }
-
- /*
- * Now run _OSC again with query flag clear and with the caps
- * supported by both the OS and the platform.
- */
- capbuf[OSC_QUERY_DWORD] = 0;
- capbuf[OSC_SUPPORT_DWORD] = capbuf_ret[OSC_SUPPORT_DWORD];
- kfree(context.ret.pointer);
- if (ACPI_FAILURE(acpi_run_osc(handle, &context)))
- return;
-
- capbuf_ret = context.ret.pointer;
- if (context.ret.length > OSC_SUPPORT_DWORD) {
#ifdef CONFIG_ACPI_CPPC_LIB
- osc_sb_cppc2_support_acked = capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_CPCV2_SUPPORT;
+ osc_sb_cppc2_support_acked = capbuf[OSC_SUPPORT_DWORD] & OSC_SB_CPCV2_SUPPORT;
#endif
- osc_sb_apei_support_acked =
- capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_APEI_SUPPORT;
- osc_pc_lpi_support_confirmed =
- capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_PCLPI_SUPPORT;
- osc_sb_native_usb4_support_confirmed =
- capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_NATIVE_USB4_SUPPORT;
- osc_cpc_flexible_adr_space_confirmed =
- capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_CPC_FLEXIBLE_ADR_SPACE;
- }
-
- kfree(context.ret.pointer);
+ osc_sb_apei_support_acked =
+ capbuf[OSC_SUPPORT_DWORD] & OSC_SB_APEI_SUPPORT;
+ osc_pc_lpi_support_confirmed =
+ capbuf[OSC_SUPPORT_DWORD] & OSC_SB_PCLPI_SUPPORT;
+ osc_sb_native_usb4_support_confirmed =
+ capbuf[OSC_SUPPORT_DWORD] & OSC_SB_NATIVE_USB4_SUPPORT;
+ osc_cpc_flexible_adr_space_confirmed =
+ capbuf[OSC_SUPPORT_DWORD] & OSC_SB_CPC_FLEXIBLE_ADR_SPACE;
}
/*
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