Messages in this thread Patch in this message | | | Date | Mon, 21 Nov 2022 21:16:40 -0800 (PST) | Subject | Re: [PATCH] cpuidle: riscv-sbi: Stop using non-retentive suspend | From | Palmer Dabbelt <> |
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On Mon, 21 Nov 2022 19:45:07 PST (-0800), anup@brainfault.org wrote: > On Tue, Nov 22, 2022 at 2:27 AM Palmer Dabbelt <palmer@rivosinc.com> wrote: >> >> From: Palmer Dabbelt <palmer@rivosinc.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@rivosinc.com> > > This is just unnecessary maintenance churn and it's not the > right way to go. Better to fix this the right way instead of having > a temporary fix. > > I had already sent-out a patch series 5 months back to describe > this in DT: > https://lore.kernel.org/lkml/20220727114302.302201-1-apatel@ventanamicro.com/ > > No one has commented/suggested anything (except Samuel > Holland and Sudeep Holla).
I see some comments from Krzysztof here <https://lore.kernel.org/lkml/7a0477a0-9f0f-87d6-4070-30321745f4cc@linaro.org/> as well. Looks like everyone is pointing out that having our CPU nodes encode timers is a bad idea, my guess is that they're probably right.
> Please review this series. I can quickly address comments to > make this available for Linux-6.2. Until this series is merged, > the affected platforms can simply remove non-retentive suspend > states from their DT.
That leaves us with a dependency between kernel versions and DT bindings: kernels with the current driver will result in broken systems with the non-retentive suspend states in the DT they boot with when those states can't wake up the CPU.
> With all due respect, NACK to this patch from my side. > > Regards, > Anup > >> >> --- >> >> 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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