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Message-Id: <20221121205647.23343-1-palmer@rivosinc.com>
Date: Mon, 21 Nov 2022 12:56:47 -0800
From: Palmer Dabbelt <palmer@...osinc.com>
To: Conor Dooley <conor@...nel.org>
Cc: anup@...infault.org, rafael@...nel.org, daniel.lezcano@...aro.org,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>, aou@...s.berkeley.edu,
linux-pm@...r.kernel.org, linux-riscv@...ts.infradead.org,
linux-kernel@...r.kernel.org, linux@...osinc.com,
Palmer Dabbelt <palmer@...osinc.com>
Subject: [PATCH] cpuidle: riscv-sbi: Stop using non-retentive suspend
From: Palmer Dabbelt <palmer@...osinc.com>
As per [1], whether or not the core can wake up from non-retentive
suspend is a platform-specific detail. We don't have any way to encode
that, so just stop using them until we've sorted that out.
Link: https://github.com/riscv-non-isa/riscv-sbi-doc/issues/98#issuecomment-1288564687
Fixes: 6abf32f1d9c5 ("cpuidle: Add RISC-V SBI CPU idle driver")
Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
---
This should allow us to revert 232ccac1bd9b ("clocksource/drivers/riscv:
Events are stopped during CPU suspend"), which fixes suspend on the D1
but breaks timers everywhere.
---
drivers/cpuidle/cpuidle-riscv-sbi.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/cpuidle/cpuidle-riscv-sbi.c b/drivers/cpuidle/cpuidle-riscv-sbi.c
index 05fe2902df9a..9d1063a54495 100644
--- a/drivers/cpuidle/cpuidle-riscv-sbi.c
+++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
@@ -214,6 +214,17 @@ static bool sbi_suspend_state_is_valid(u32 state)
if (state > SBI_HSM_SUSPEND_NON_RET_DEFAULT &&
state < SBI_HSM_SUSPEND_NON_RET_PLATFORM)
return false;
+
+ /*
+ * Whether or not RISC-V systems deliver interrupts to harts in a
+ * non-retentive suspend state is a platform-specific detail. This can
+ * leave the hart unable to wake up, so just mark these states as
+ * unsupported until we have a mechanism to expose these
+ * platform-specific details to Linux.
+ */
+ if (state & SBI_HSM_SUSP_NON_RET_BIT)
+ return false;
+
return true;
}
--
2.38.1
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