On Mon, Jan 21, 2019 at 4:17 PM Vincent Guittot <vincent.guittot@xxxxxxxxxx> wrote: > > On Fri, 18 Jan 2019 at 13:08, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > > > On 1/18/19 3:05 AM, Rafael J. Wysocki wrote: > > > On Fri, Jan 18, 2019 at 11:53 AM Vincent Guittot > > > <vincent.guittot@xxxxxxxxxx> wrote: > > >> > > >> On Fri, 18 Jan 2019 at 11:42, Vincent Guittot > > >> <vincent.guittot@xxxxxxxxxx> wrote: > > >>> > > >>> Hi Guenter, > > >>> > > >>> Le Thursday 17 Jan 2019 à 14:16:28 (-0800), Guenter Roeck a écrit : > > >>>> On Fri, Dec 21, 2018 at 11:33:56AM +0100, Vincent Guittot wrote: > > >>>>> From: Thara Gopinath <thara.gopinath@xxxxxxxxxx> > > >>>>> > > >>>>> This patch replaces jiffies based accounting for runtime_active_time > > >>>>> and runtime_suspended_time with ktime base accounting. This makes the > > >>>>> runtime debug counters inline with genpd and other pm subsytems which > > >>>>> uses ktime based accounting. > > >>>>> > > >>>>> timekeeping is initialized before pm_runtime_init() so ktime_get() will > > >>>>> be ready before first call. In fact, timekeeping_init() is called early > > >>>>> in start_kernel() which is way before driver_init() (and that's when > > >>>>> devices can start to be initialized) called from rest_init() via > > >>>>> kernel_init_freeable() and do_basic_setup(). > > >>>>> > > >>>> This is not (always) correct. My qemu "collie" boot test fails with this > > >>>> patch applied. Reverting the patch fixes the problem. Bisect log attached. > > >>>> > > >>> > > >>> Can you try the patch below ? > > >>> ktime_get_mono_fast_ns() has the advantage of being init with dummy clock so > > >>> it can be used at early_init. > > >> > > >> Another possibility would be delay the init of the gpiochip > > > > > > Well, right. > > > > > > Initializing devices before timekeeping doesn't feel particularly > > > robust from the design perspective. > > > > > > How exactly does that happen? > > > > > > > With an added 'initialized' flag and backtrace into the timekeeping code, > > with the change suggested earlier applied: > > > > ------------[ cut here ]------------ > > WARNING: CPU: 0 PID: 0 at kernel/time/timekeeping.c:453 ktime_get_mono_fast_ns+0x114/0x12c > > Timekeeping not initialized > > CPU: 0 PID: 0 Comm: swapper Not tainted 5.0.0-rc2-next-20190117-dirty #2 > > Hardware name: Sharp-Collie > > Backtrace: > > [<c000dce8>] (dump_backtrace) from [<c000df78>] (show_stack+0x18/0x1c) > > r7:00000009 r6:00000000 r5:c065ba90 r4:c06d3e54 > > [<c000df60>] (show_stack) from [<c0588930>] (dump_stack+0x20/0x28) > > [<c0588910>] (dump_stack) from [<c0018ae8>] (__warn+0xcc/0xf4) > > [<c0018a1c>] (__warn) from [<c0018b5c>] (warn_slowpath_fmt+0x4c/0x6c) > > r8:df407b08 r7:00000000 r6:c0c01550 r5:c065bad8 r4:c06dd028 > > [<c0018b14>] (warn_slowpath_fmt) from [<c0069e2c>] (ktime_get_mono_fast_ns+0x114/0x12c) > > r3:00000000 r2:c065bad8 > > r5:00000000 r4:df407b08 > > [<c0069d18>] (ktime_get_mono_fast_ns) from [<c03c7810>] (pm_runtime_init+0x38/0xb8) > > r9:c06c9a5c r8:df407b08 r7:00000000 r6:c0c01550 r5:00000000 r4:df407b08 > > [<c03c77d8>] (pm_runtime_init) from [<c03b6a34>] (device_initialize+0xb0/0xec) > > r7:00000000 r6:c0c01550 r5:00000000 r4:df407b08 > > [<c03b6984>] (device_initialize) from [<c0366d30>] (gpiochip_add_data_with_key+0x9c/0x884) > > r7:00000000 r6:c06fca34 r5:00000000 r4:00000000 > > [<c0366c94>] (gpiochip_add_data_with_key) from [<c06b9708>] (sa1100_init_gpio+0x40/0x98) > > r10:dfffcd60 r9:c06c9a5c r8:c06dd020 r7:c06dd028 r6:ffffffff r5:00000000 > > r4:c06fca34 > > [<c06b96c8>] (sa1100_init_gpio) from [<c06ae58c>] (sa1100_init_irq+0x2c/0x3c) > > r7:c06dd028 r6:ffffffff r5:c0713300 r4:c06e1070 > > [<c06ae560>] (sa1100_init_irq) from [<c06aab1c>] (init_IRQ+0x20/0x28) > > r5:c0713300 r4:00000000 > > [<c06aaafc>] (init_IRQ) from [<c06a7cd0>] (start_kernel+0x254/0x4cc) > > [<c06a7a7c>] (start_kernel) from [<00000000>] ( (null)) > > r10:0000717f r9:6901b119 r8:c0000100 r7:00000092 r6:0000313d r5:00000053 > > r4:c06a7330 > > ---[ end trace 91e1bd00dd7cce32 ]--- > > Does it means that only the pm_runtime_init is done before > timekeeping_init() but no update_pm_runtime_accounting() ? This platform calls device_initialize(), via sa1100_init_irq(), from init_IRQ() which is in the start_kernel() code path before timekeeping_init(). That's the initialization of structure fields alone. Runtime PM really cannot be used legitimately before driver_init(), because it needs bus types to be there at least. > In this case, we can keep using ktimeçget in > update_pm_runtime_accounting() and find a solution to deal with > early_call of pm_runtime_init() Given the above, I think that initializing accounting_timestamp in pm_runtime_init() to anything different from 0 is a mistake. Note that update_pm_runtime_accounting() ignores the delta value if power.disable_depth is not zero anyway, so it really should be sufficient to update accounting_timestamp when enabling runtime PM - and I'm not sure why it is not updated in pm_runtime_enable() for that matter (that looks like a bug to me). _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
