(EXT) Re: [PATCH v2 3/3] clk: Drop the rate range on clk_put
Maxime Ripard
maxime at cerno.tech
Fri Apr 1 05:27:36 PDT 2022
Hi Alexander, Tony, Marek,
On Fri, Apr 01, 2022 at 01:55:20PM +0200, Alexander Stein wrote:
> Am Donnerstag, 31. März 2022, 17:31:34 CEST schrieb Maxime Ripard:
> > * PGP Signed by an unknown key
> >
> > Hi Tony,
> >
> > On Thu, Mar 31, 2022 at 06:00:42PM +0300, Tony Lindgren wrote:
> > > * Maxime Ripard <maxime at cerno.tech> [220331 09:52]:
> > > > On Thu, Mar 31, 2022 at 12:42:10PM +0300, Tony Lindgren wrote:
> > > > > It seems the dts assigned-clock-parents no longer works now?
> > > >
> > > > That would make some kind of sense, __set_clk_parents calls clk_put on
> > > > both the assigned clock and its parent.
> > > >
> > > > Could you see what parent (and why?) it tries to enforce then?
> > >
> > > It picks the other option available for the mux clock that only has
> > > two options. No idea why, but if you have some debug patch in mind I
> > > can give it a try.
> > >
> > > > It looks like the gpt1_fck driver might favor another parent for that
> > > > rate, which, if it's an invalid configuration, shouldn't really happen?
> > >
> > > Hmm there's a gate clock and a mux clock, there's not really a rate
> > > selection available here for the sources.
> >
> > If I followed the OMAP driver properly, clk_mux_determine_rate_flags is
> > doing the heavy lifting, could you run your test with
>
> I'm affected by this patch as well on an imx8mp platform (see [1] for some
> details)
>
> In the failing case with with your patch applied I get the following error
> ---
> [ 0.661064] clk_set_rate_range_nolock: core req rate 500000000
> [ 0.664084] clk_set_rate_range_nolock: clamped rate 500000000
> [ 0.669851] clk_core_set_rate_nolock: rate 500000000
> [ 0.674843] clk_core_set_rate_nolock: rounded rate 500000000
> [ 0.680536] clk_set_rate_range_nolock: core req rate 800000000
> [ 0.686389] clk_set_rate_range_nolock: clamped rate 800000000
> [ 0.692164] clk_core_set_rate_nolock: rate 800000000
> [ 0.697153] clk_mux_determine_rate_flags: requested rate 800000000
> [ 0.703363] clk_mux_determine_rate_flags: current parent sys_pll1
> [ 0.709487] clk_mux_determine_rate_flags: current parent rate 800000000
> [ 0.716147] Unable to handle kernel NULL pointer dereference at virtual
> address 0000000000000000
> [ 0.724977] Mem abort info:
> [ 0.727775] ESR = 0x96000004
> [ 0.730835] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 0.736177] SET = 0, FnV = 0
> [ 0.739239] EA = 0, S1PTW = 0
> [ 0.742382] FSC = 0x04: level 0 translation fault
> [ 0.747287] Data abort info:
> [ 0.750172] ISV = 0, ISS = 0x00000004
> [ 0.754027] CM = 0, WnR = 0
> [ 0.757002] [0000000000000000] user address but active_mm is swapper
> [ 0.763394] Internal error: Oops: 96000004 [#1] PREEMPT SMP
> [ 0.768985] Modules linked in:
> [ 0.772049] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.17.0-next-20220331+
> #48 8e9d24095c7f6b15f85bc2ad57a5609e219130b9
> [ 0.782984] Hardware name: TQ-Systems i.MX8MPlus TQMa8MPxL on MBa8MPxL (DT)
> [ 0.789985] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 0.796985] pc : clk_mux_determine_rate_flags+0x280/0x2cc
> [ 0.802407] lr : clk_mux_determine_rate_flags+0xf4/0x2cc
> [ 0.807747] sp : ffff800009ceb590
> [ 0.811072] x29: ffff800009ceb590 x28: ffff800009ceb6a0 x27:
> ffff800008eaa038
> [ 0.818245] x26: ffff8000092fe0b0 x25: ffff000000090000 x24:
> ffff000000090000
> [ 0.825420] x23: 0000000000000000 x22: ffff800008ea95d8 x21:
> ffff0000028f4700
> [ 0.832595] x20: 000000002faf0800 x19: 0000000000000000 x18:
> 0000000000004590
> [ 0.839770] x17: 0000000000004570 x16: 0000000000004560 x15:
> ffff8000092ff250
> [ 0.846945] x14: 0000000000000000 x13: 3030303030303030 x12:
> 3820657461722074
> [ 0.854120] x11: 6e6572617020746e x10: 6572727563203a73 x9 :
> 7563203a7367616c
> [ 0.861295] x8 : 665f657461725f65 x7 : 205d373834393037 x6 :
> ffff800009a947c8
> [ 0.868472] x5 : ffff800008eafe68 x4 : 0000000000000009 x3 :
> 000000002faf0800
> [ 0.875645] x2 : ffff800008eafef4 x1 : ffff800008eaa038 x0 :
> ffff8000092fd5b8
> [ 0.882822] Call trace:
> [ 0.885273] clk_mux_determine_rate_flags+0x280/0x2cc
> [ 0.890347] clk_mux_determine_rate+0x10/0x20
> [ 0.894720] clk_core_determine_round_nolock+0x4c/0xb4
> [ 0.899882] clk_core_round_rate_nolock+0x30/0x80
> [ 0.904607] clk_core_round_rate_nolock+0x70/0x80
> [ 0.909334] clk_hw_round_rate+0x44/0x74
> [ 0.913270] clk_factor_round_rate+0x60/0x80
> [ 0.917557] clk_core_determine_round_nolock+0x88/0xb4
> [ 0.922720] clk_core_round_rate_nolock+0x30/0x80
> [ 0.927445] clk_core_set_rate_nolock.part.0+0xa4/0x1d0
> [ 0.932695] clk_set_rate_range_nolock+0x234/0x244
> [ 0.937507] __clk_put+0x60/0x12c
> [ 0.940834] clk_put+0xc/0x1c
> [ 0.943809] __set_clk_parents+0x12c/0x244
> [ 0.947920] of_clk_set_defaults+0x20/0x50
> [ 0.952032] of_clk_add_hw_provider.part.0+0x94/0x120
> [ 0.957107] of_clk_add_hw_provider+0x10/0x20
> [ 0.961482] imx8mp_clocks_probe+0x3458/0x34d0
> [ 0.965945] platform_probe+0x64/0x100
> [ 0.969707] call_driver_probe+0x28/0x130
> [ 0.973732] really_probe+0x178/0x310
> [ 0.977409] __driver_probe_device+0xfc/0x144
> [ 0.981782] driver_probe_device+0x38/0x12c
> [ 0.985982] __driver_attach+0xcc/0x220
> [ 0.989834] bus_for_each_dev+0x6c/0xc0
> [ 0.993682] driver_attach+0x20/0x2c
> [ 0.997270] bus_add_driver+0x140/0x230
> [ 1.001120] driver_register+0x74/0x120
> [ 1.004970] __platform_driver_register+0x24/0x30
> [ 1.009697] imx8mp_clk_driver_init+0x18/0x20
> [ 1.014070] do_one_initcall+0x58/0x200
> [ 1.017920] do_initcalls+0x164/0x19c
> [ 1.021597] kernel_init_freeable+0x134/0x17c
> [ 1.025970] kernel_init+0x2c/0x150
> [ 1.029470] ret_from_fork+0x10/0x20
> [ 1.033065] Code: f9000f94 912982c1 b0002900 9116e000 (f9400262)
> [ 1.039188] ---[ end trace 0000000000000000 ]---
> [ 1.043869] Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x0000000b
> [ 1.051523] SMP: stopping secondary CPUs
> [ 1.055467] Kernel Offset: disabled
> [ 1.058960] CPU features: 0x000,00020009,00001082
> [ 1.063684] Memory Limit: none
> [ 1.066748] ---[ end Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x0000000b ]---
> ---
>
> With the $subject patch reverted and bootable system:
> ---
> [ 0.659922] clk_core_set_rate_nolock: rate 1000000000
> [ 0.662154] clk_core_set_rate_nolock: rounded rate 1000000000
> [ 0.667932] clk_core_set_rate_nolock: rate 800000000
> [ 0.672918] clk_core_set_rate_nolock: rounded rate 800000000
> [ 0.678601] clk_core_set_rate_nolock: rate 500000000
> [ 0.683592] clk_core_set_rate_nolock: rounded rate 500000000
> [ 0.689276] clk_core_set_rate_nolock: rate 400000000
> [ 0.694267] clk_core_set_rate_nolock: rounded rate 400000000
> [ 0.699980] clk_core_set_rate_nolock: rate 800000000
> [ 0.704942] clk_core_set_rate_nolock: rounded rate 800000000
> [ 0.710627] clk_core_set_rate_nolock: rate 393216000
> [ 0.715611] clk_core_set_rate_nolock: rounded rate 393216000
> [ 0.721815] clk_core_set_rate_nolock: rate 361267200
> [ 0.726284] clk_core_set_rate_nolock: rounded rate 361267200
> [ 0.734097] clk_core_set_rate_nolock: rate 800000000
> [ 0.736977] clk_core_set_rate_nolock: rounded rate 800000000
> [ 0.742652] clk_core_set_rate_nolock: rate 400000000
> [ 0.747645] clk_core_set_rate_nolock: rounded rate 400000000
> [ 0.754565] clk_core_set_rate_nolock: rate 500000000
> [ 0.758331] clk_core_set_rate_nolock: rounded rate 500000000
> [ 0.764688] SoC: i.MX8MP revision 1.1
> [ 0.767931] clk_core_set_rate_nolock: rate 500000000
> [ 0.772675] clk_core_set_rate_nolock: rounded rate 500000000
> [ 0.778354] clk_core_set_rate_nolock: rate 200000000
> [ 0.783351] clk_core_set_rate_nolock: rounded rate 200000000
> [ 0.793748] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> [ 0.798952] 30860000.serial: ttymxc0 at MMIO 0x30860000 (irq = 34,
> base_baud = 5000000) is a IMX
> [ 0.806527] 30880000.serial: ttymxc2 at MMIO 0x30880000 (irq = 35,
> base_baud = 5000000) is a IMX
> [ 0.815329] 30890000.serial: ttymxc1 at MMIO 0x30890000 (irq = 36,
> base_baud = 5000000) is a IMX
> [ 0.824176] 30a60000.serial: ttymxc3 at MMIO 0x30a60000 (irq = 43,
> base_baud = 1500000) is a IMX
> [ 0.832588] printk: console [ttymxc3] enabled
> [ 0.832588] printk: console [ttymxc3] enabled
> [ 0.841244] printk: bootconsole [ec_imx6q0] disabled
> [ 0.841244] printk: bootconsole [ec_imx6q0] disabled
> [ 0.857871] clk_core_set_rate_nolock: rate 80000000
> [ 0.862796] clk_core_set_rate_nolock: rounded rate 80000000
> [ 0.868469] clk_core_set_rate_nolock: rate 20000000
> [ 0.873364] clk_core_set_rate_nolock: rounded rate 20000000
> [ 0.879258] clk_core_set_rate_nolock: rate 80000000
> [ 0.884154] clk_core_set_rate_nolock: rounded rate 80000000
> [...]
> ---
>
> The 500000000 and 800000000 look a bit like the assigned-clock-rates for
> clock-controller at 30380000 in arch/arm64/boot/dts/freescale/imx8mp.dtsi
>
> If you need some more information, do not hesitate to ask
Thanks a lot to you three for all your testing. I think I know what
might be going on:
We use the last requested rate on clk_set_rate_range
(clk_core.req_rate), and that requested rate if the clock is orphan will
be set to 0, so if we were to call clk_set_rate_range before the parent
clock is registered, we would effectively call a clk_set_rate to 0
And the assigned-clocks stuff is handled by __set_clk_parents and
__set_clk_rates, called by of_clk_set_defaults(), in turn called by
of_clk_init and of_clk_add_provider. Both __set_clk_parents and
__set_clk_rates will call clk_put once done with the clock, and we will
with this patch trigger the clk_set_rate to 0 I mentioned before.
So we just became very good at triggering the underlying issue :)
And I think it's that while we update the requested rate when the
missing parent is registered, we never do when we mux away from it using
clk_set_parent.
Could you test the following patch and let me know if it works?
--->8---
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 91f863b7a824..ee5a0223e47d 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2599,6 +2599,8 @@ static int clk_core_set_parent_nolock(struct clk_core *core,
} else {
__clk_recalc_rates(core, POST_RATE_CHANGE);
__clk_recalc_accuracies(core);
+
+ core->req_rate = core->rate;
}
runtime_put:
--->8---
Thanks!
Maxime
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