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Message-ID: <Y4FTQenbPLXy/9Bz@spud> Date: Fri, 25 Nov 2022 23:44:01 +0000 From: Conor Dooley <conor@...nel.org> To: Anup Patel <apatel@...tanamicro.com> Cc: Anup Patel <apatel@...tanamicro.com>, Rob Herring <robh+dt@...nel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Palmer Dabbelt <palmer@...belt.com>, Paul Walmsley <paul.walmsley@...ive.com>, Daniel Lezcano <daniel.lezcano@...aro.org>, Thomas Gleixner <tglx@...utronix.de>, Andrew Jones <ajones@...tanamicro.com>, Atish Patra <atishp@...shpatra.org>, Samuel Holland <samuel@...lland.org>, Anup Patel <anup@...infault.org>, devicetree@...r.kernel.org, linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, Jisheng Zhang <jszhang@...nel.org> Subject: Re: [PATCH v3 3/3] clocksource: timer-riscv: Set CLOCK_EVT_FEAT_C3STOP based on DT On Fri, Nov 25, 2022 at 01:13:04PM +0000, Conor Dooley wrote: > On Fri, Nov 25, 2022 at 04:51:05PM +0530, Anup Patel wrote: > > We should set CLOCK_EVT_FEAT_C3STOP for a clock_event_device only > > when riscv,timer-cant-wake-up DT property is present in the RISC-V > > timer DT node. > > > > This way CLOCK_EVT_FEAT_C3STOP feature is set for clock_event_device > > based on RISC-V platform capabilities rather than having it set for > > all RISC-V platforms. > > I need to go do some testing on what setting the C3STOP flag does on > platforms other than PolarFire SoC. I'm not sure that we should be > enabling this flag *at all* until we know that it does not break on > other platforms too. I tried my fu540 & fu740 - both of those seem to exhibit broken timer behaviour with C3STOP set. Ethernet doesn't work upstream on the VisionFive, so I didn't go through the hassle of testing that - but I would imagine it is the same as the fu740. Whenever I get a VisionFive 2 I'll give that a try too. I did try the D1 (thanks for fielding my dumb questions Samuel) but I was not able to get the thing to boot if I disabled the sunxi timer :/ Ethernet would not come up in U-Boot, clearly I did something not right.. Obviously we need to fix things & get it backported etc, so taking a pragmatic approach: I think that it is better to merge this stuff even though it there's a pretty good chance I think that it'll break the SBI timer on a D1, since it is not intended that it will be used. It does make me worried about some of the other platforms though, like that Bouffalolabs SoC that Jisheng sent in a DT for. It's also using thead stuff so I wonder if it needs C3STOP too. I've added Jisheng to CC :) > > Signed-off-by: Anup Patel <apatel@...tanamicro.com> > > --- > > drivers/clocksource/timer-riscv.c | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c > > index a0d66fabf073..0c8bdd168a45 100644 > > --- a/drivers/clocksource/timer-riscv.c > > +++ b/drivers/clocksource/timer-riscv.c > > @@ -28,6 +28,7 @@ > > #include <asm/timex.h> > > > > static DEFINE_STATIC_KEY_FALSE(riscv_sstc_available); > > +static bool riscv_timer_cant_wake_cpu; > > > > static int riscv_clock_next_event(unsigned long delta, > > struct clock_event_device *ce) > > @@ -85,6 +86,8 @@ static int riscv_timer_starting_cpu(unsigned int cpu) > > > > ce->cpumask = cpumask_of(cpu); > > ce->irq = riscv_clock_event_irq; > > + if (riscv_timer_cant_wake_cpu) > > + ce->features |= CLOCK_EVT_FEAT_C3STOP; > > clockevents_config_and_register(ce, riscv_timebase, 100, 0x7fffffff); > > > > enable_percpu_irq(riscv_clock_event_irq, > > @@ -139,6 +142,13 @@ static int __init riscv_timer_init_dt(struct device_node *n) > > if (cpuid != smp_processor_id()) > > return 0; > > > > + child = of_find_compatible_node(NULL, NULL, "riscv,timer"); > > + if (child) { > > + riscv_timer_cant_wake_cpu = of_property_read_bool(child, > > + "riscv,timer-cant-wake-cpu"); > > + of_node_put(child); > > + } > > + > > domain = NULL; > > child = of_get_compatible_child(n, "riscv,cpu-intc"); > > if (!child) { Anyway, the mechanics of the change here look good to me. The re-use of child is understandable but a little odd though, since riscv,timer /is not/ actually a child. That's relatively minor thing to change though. I'm still not happy about turning on C3STOP when we have not figured out why it's breaking timer behaviour, but I think that's the lessor of two evils. Somewhat reluctantly: Reviewed-by: Conor Dooley <conor.dooley@...rochip.com> I'll try to spend some time looking into why it's broken. Thanks, Conor.
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