linux-kernel - [PATCH v1 2/2] ACPI: bus: Adjust acpi_bus_osc_negotiate_platform

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Message-ID: <4703755.LvFx2qVVIh@rafael.j.wysocki>
Date: Tue, 16 Dec 2025 21:18:27 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux ACPI <linux-acpi@...r.kernel.org>
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 v1 2/2] ACPI: bus: Adjust acpi_bus_osc_negotiate_platform_control()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Remove checks that have become redundant after a previous change from
acpi_bus_osc_negotiate_platform_control(), add a debug statement
regarding the negotiated support bit mask to it and add an empty
code line to it for more clarity.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/bus.c |   28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -319,7 +319,7 @@ 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;
+	u32 capbuf[2], *capbuf_ret, ret_support;
 	struct acpi_osc_context context = {
 		.uuid_str = sb_uuid_str,
 		.rev = 1,
@@ -371,6 +371,7 @@ static void acpi_bus_osc_negotiate_platf
 
 	if (!ghes_disable)
 		capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_APEI_SUPPORT;
+
 	if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle)))
 		return;
 
@@ -378,10 +379,9 @@ static void acpi_bus_osc_negotiate_platf
 		return;
 
 	capbuf_ret = context.ret.pointer;
-	if (context.ret.length <= OSC_SUPPORT_DWORD) {
-		kfree(context.ret.pointer);
-		return;
-	}
+
+	acpi_handle_debug(handle, "Negotiated _OSC mask [%04x]\n",
+			  capbuf_ret[OSC_SUPPORT_DWORD]);
 
 	/*
 	 * Now run _OSC again with query flag clear and with the caps
@@ -395,20 +395,14 @@ static void acpi_bus_osc_negotiate_platf
 		return;
 
 	capbuf_ret = context.ret.pointer;
-	if (context.ret.length > OSC_SUPPORT_DWORD) {
+	ret_support = capbuf_ret[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 = ret_support & 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;
-	}
+	osc_sb_apei_support_acked = ret_support & OSC_SB_APEI_SUPPORT;
+	osc_pc_lpi_support_confirmed = ret_support & OSC_SB_PCLPI_SUPPORT;
+	osc_sb_native_usb4_support_confirmed = ret_support & OSC_SB_NATIVE_USB4_SUPPORT;
+	osc_cpc_flexible_adr_space_confirmed = ret_support & OSC_SB_CPC_FLEXIBLE_ADR_SPACE;
 
 	kfree(context.ret.pointer);
 }