FAILED: patch "[PATCH] riscv: acpi: Handle LPI architectural context loss flags" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 7e4cb63d61a7e0bef20f0d00e831c7fac06e4a1c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026090302-tropics-obstinate-fff5@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7e4cb63d61a7e0bef20f0d00e831c7fac06e4a1c Mon Sep 17 00:00:00 2001
From: Peixin Xie <[email protected]>
Date: Fri, 7 Aug 2026 19:24:32 -0600
Subject: [PATCH] riscv: acpi: Handle LPI architectural context loss flags

Commit 4785aa802853 ("cpuidle, ACPI: Evaluate LPI arch_flags for broadcast timer") replaced the generic nonzero check for LPI architectural context loss flags with arch_get_idle_state_flags(). RISC-V does not implement the helper, so it falls back to the stub that returns 0. Consequently, CPUIDLE_FLAG_TIMER_STOP is not set when an LPI state loses the hart timer context, preventing cpuidle from using a broadcast timer for that state.

Implement the RISC-V helper and map the hart timer context loss flag to CPUIDLE_FLAG_TIMER_STOP.

index d59bd06347cc..980aa11d7741 100644
@@ -12,6 +12,8 @@
 #ifndef _ASM_ACPI_H
 #define _ASM_ACPI_H
 
+#include <linux/cpuidle.h>
+
 /* Basic configuration for ACPI */
 #ifdef CONFIG_ACPI
 

@@ -67,6 +69,23 @@ int acpi_get_riscv_isa(struct acpi_table_header *table,
 
 void acpi_get_cbo_block_size(struct acpi_table_header *table, u32 *cbom_size,
 			     u32 *cboz_size, u32 *cbop_size);
+
+/*
+ * RISC-V Functional Fixed Hardware Specification Version v1.0.1,
+ * Chapter 3.1.2, Table 4: Arch. Context Lost Flags
+ */
+#define RISCV_LPI_HART_TIMER_CTXT_LOST		BIT(0)
+
+static inline unsigned int arch_get_idle_state_flags(u32 arch_flags)
+{
+	if (arch_flags & RISCV_LPI_HART_TIMER_CTXT_LOST)
+		return CPUIDLE_FLAG_TIMER_STOP;
+
+	return 0;
+}
+
+#define arch_get_idle_state_flags arch_get_idle_state_flags
+
 #else
 static inline void acpi_init_rintc_map(void) { }
 static inline struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)