Message-ID: <Zn5ZEI1m4jImz/Wp@hu-varada-blr.qualcomm.com>
Date: Fri, 28 Jun 2024 12:02:48 +0530
From: Varadarajan Narayanan <quic_varada@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: <robh@...nel.org>, <krzk+dt@...nel.org>, <conor+dt@...nel.org>,
        <angelogioacchino.delregno@...labora.com>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <mturquette@...libre.com>,
        <sboyd@...nel.org>, <ilia.lin@...nel.org>, <rafael@...nel.org>,
        <viresh.kumar@...aro.org>, <ulf.hansson@...aro.org>,
        <quic_sibis@...cinc.com>, <otto.pflueger@...cue.de>,
        <neil.armstrong@...aro.org>, <luca@...tu.xyz>, <abel.vesa@...aro.org>,
        <danila@...xyga.com>, <quic_ipkumar@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v3 2/9] cpufreq: qcom-nvmem: Add genpd names to
 match_data_kryo

On Wed, Jun 26, 2024 at 09:23:17PM +0300, Dmitry Baryshkov wrote:
> On Wed, Jun 26, 2024 at 04:09:55PM GMT, Varadarajan Narayanan wrote:
> > This is used for tying up the cpu@N nodes with the power domains.
> > Without this, 'cat /sys/kernel/debug/qcom_cpr3/thread0'
> > crashes with NULL pointer access.
>
> Add the interesting part of the backtrace, please.

        if (thread->drv->desc->cpr_type < CTRL_TYPE_CPRH) {
                seq_printf(s, "current_volt = %d uV\n", thread->drv->last_uV);
                seq_printf(s, "requested voltage: %d uV\n", thread->corner->last_uV);
        }

thread->corner is NULL in the second printf above.

	# cat /sys/kernel/debug/qcom_cpr3/thread0
	[   16.965241] Unable to handle kernel NULL pointer dereference at virtual address 000000000000000c
	[   16.965270] Mem abort info:
	[   16.973181]   ESR = 0x0000000096000004
	[   16.975607]   EC = 0x25: DABT (current EL), IL = 32 bits
	[   16.979425]   SET = 0, FnV = 0
	[   16.984889]   EA = 0, S1PTW = 0
	[   16.987756]   FSC = 0x04: level 0 translation fault
	[   16.990792] Data abort info:
	[   16.995652]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
	[   16.998779]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
	[   17.004074]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
	[   17.009196] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000481b1000
	[   17.014579] [000000000000000c] pgd=0000000000000000, p4d=0000000000000000
	[   17.020919] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
	[   17.020921] Modules linked in:
	[   17.020926] CPU: 0 UID: 0 PID: 118 Comm: cat Not tainted 6.10.0-rc4-next-20240620-00020-g125eb3184fc1-dirty #9
	[   17.020931] Hardware name: Qualcomm Technologies, Inc. IPQ9574/AP-AL02-C7 (DT)
	[   17.020933] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
	[   17.020936] pc : cpr3_debug_info_show+0x3a0/0x3ac
	[   17.020945] lr : cpr3_debug_info_show+0x390/0x3ac
	[   17.020948] sp : ffff800086293b90
	[   17.020949] x29: ffff800086293b90 x28: ffff0000034ae038 x27: 0000000000400cc0
	[   17.020953] x26: 000000007ffff000 x25: ffff0000034ae028 x24: 0000000000000000
	[   17.020957] x23: ffff800086293c80 x22: ffff000002399880 x21: ffff000002a8fa80
	[   17.020960] x20: ffff0000034ae000 x19: 0000000000000000 x18: ffffffffffffffff
	[   17.020964] x17: 0000000000000000 x16: 0000000000000000 x15: ffff800086293a40
	[   17.020967] x14: ffff000002913000 x13: ffff00000291200f x12: 0000000000000000
	[   17.020970] x11: 0000000000000000 x10: 0000000000000000 x9 : ffff0000034a9000
	[   17.020973] x8 : 000000000a567520 x7 : 0000000000000001 x6 : 000000000a567520
	[   17.020976] x5 : ffff000002912014 x4 : ffff800080e1f3a5 x3 : 0000000000000014
	[   17.020979] x2 : 0000000000000000 x1 : ffff800080e1f848 x0 : ffff0000034ae000
	[   17.020983] Call trace:
	[   17.020984]  cpr3_debug_info_show+0x3a0/0x3ac
	[   17.020987]  seq_read_iter+0xe0/0x45c
	[   17.020993]  seq_read+0xec/0x130
	[   17.020996]  full_proxy_read+0x60/0xb4
	[   17.020999]  vfs_read+0xc0/0x31c
	[   17.021003]  ksys_read+0x70/0x104
	[   17.021006]  __arm64_sys_read+0x1c/0x28
	[   17.021008]  invoke_syscall+0x48/0x114
	[   17.021014]  el0_svc_common+0x3c/0xe8
	[   17.021017]  do_el0_svc+0x20/0x2c
	[   17.021020]  el0_svc+0x34/0xd8
	[   17.021024]  el0t_64_sync_handler+0x120/0x12c
	[   17.021027]  el0t_64_sync+0x190/0x194
	[   17.021031] Code: f94012c2 aa1403e0 b0004701 91212021 (b9400c42)
	[   17.021033] ---[ end trace 0000000000000000 ]---
	Segmentation fault

> > Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
> > ---
> >  drivers/cpufreq/qcom-cpufreq-nvmem.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/cpufreq/qcom-cpufreq-nvmem.c b/drivers/cpufreq/qcom-cpufreq-nvmem.c
> > index 939702dfa73f..5e6525c7788c 100644
> > --- a/drivers/cpufreq/qcom-cpufreq-nvmem.c
> > +++ b/drivers/cpufreq/qcom-cpufreq-nvmem.c
> > @@ -399,6 +399,7 @@ static const char *generic_genpd_names[] = { "perf", NULL };
> >
> >  static const struct qcom_cpufreq_match_data match_data_kryo = {
> >  	.get_version = qcom_cpufreq_kryo_name_version,
> > +	.genpd_names = generic_genpd_names,
>
> This forces that every Kryo SoC has "perf" genpd, which obviously isn't
> corret (at least from the upstream support point of view).

While trying to get the above backtrace, randomly during boot
I see the following BUG too.

	[    1.562847] ------------[ cut here ]------------
	[    1.574342] kernel BUG at drivers/cpufreq/cpufreq.c:1542!
	[    1.579203] Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
	[    1.579209] Modules linked in:
	[    1.579217] CPU: 2 UID: 0 PID: 11 Comm: kworker/u16:0 Not tainted 6.10.0-rc4-next-20240620-00020-g125eb3184fc1-dirty #10
	[    1.579227] Hardware name: Qualcomm Technologies, Inc. IPQ9574/AP-AL02-C7 (DT)
	[    1.579232] Workqueue: events_unbound deferred_probe_work_func
	[    1.579249] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
	[    1.579257] pc : cpufreq_online+0x938/0x954
	[    1.579271] lr : cpufreq_online+0x788/0x954
	[    1.579281] sp : ffff8000817c3520
	[    1.579283] x29: ffff8000817c3520 x28: ffff0000029efa50 x27: 0000000000000001
	[    1.579294] x26: 0000000000000001 x25: ffff8000814d8da0 x24: 0000000000000000
	[    1.579303] x23: ffff0000029ef9d0 x22: ffff800081735000 x21: 0000000000000000
	[    1.579312] x20: 00000000000c15c0 x19: ffff0000029ef800 x18: ffff00000183481c
	[    1.579321] x17: ffff8000818a3638 x16: 0000000000000000 x15: ffff8000818a3670
	[    1.579330] x14: 0000000000000003 x13: ffff00000192b140 x12: ffff8000814d8c58
	[    1.579338] x11: ffff00000192b140 x10: 00000000000009b0 x9 : ffff8000817c3240
	[    1.579347] x8 : ffff00000192bad0 x7 : 0000000000000001 x6 : ffff8000814d8da0
	[    1.579355] x5 : ffff8000812c32d0 x4 : 0000000000000000 x3 : 0000000000000000
	[    1.579363] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 00000000fffffff0
	[    1.579372] Call trace:
	[    1.579375]  cpufreq_online+0x938/0x954
	[    1.579386]  cpufreq_add_dev+0x80/0x98
	[    1.579395]  subsys_interface_register+0x100/0x130
	[    1.579404]  cpufreq_register_driver+0x150/0x244
	[    1.579413]  dt_cpufreq_probe+0x8c/0x440
	[    1.579420]  platform_probe+0x68/0xc8
	[    1.579430]  really_probe+0xbc/0x29c
	[    1.579438]  __driver_probe_device+0x78/0x12c
	[    1.579446]  driver_probe_device+0xd8/0x15c
	[    1.579454]  __device_attach_driver+0xb8/0x134
	[    1.579463]  bus_for_each_drv+0x84/0xe0
	[    1.579470]  __device_attach+0x9c/0x188
	[    1.579478]  device_initial_probe+0x14/0x20
	[    1.579487]  bus_probe_device+0xac/0xb0
	[    1.579494]  device_add+0x55c/0x720
	[    1.579500]  platform_device_add+0x1b8/0x244
	[    1.579510]  platform_device_register_full+0xfc/0x184
	[    1.579516]  platform_device_register_resndata.constprop.0+0x5c/0x8c
	[    1.579524]  qcom_cpufreq_probe+0x1e4/0x498
	[    1.579531]  platform_probe+0x68/0xc8
	[    1.579540]  really_probe+0xbc/0x29c
	[    1.579548]  __driver_probe_device+0x78/0x12c
	[    1.579556]  driver_probe_device+0xd8/0x15c
	[    1.579564]  __device_attach_driver+0xb8/0x134
	[    1.579573]  bus_for_each_drv+0x84/0xe0
	[    1.579580]  __device_attach+0x9c/0x188
	[    1.579588]  device_initial_probe+0x14/0x20
	[    1.579596]  bus_probe_device+0xac/0xb0
	[    1.579603]  deferred_probe_work_func+0x88/0xc0
	[    1.579611]  process_one_work+0x148/0x28c
	[    1.579623]  worker_thread+0x2e8/0x3f8
	[    1.579633]  kthread+0x110/0x114
	[    1.579641]  ret_from_fork+0x10/0x20
	[    1.579653] Code: aa1703e0 52800021 97e38ed5 17ffffea (d4210000)
	[    1.579657] ---[ end trace 0000000000000000 ]---
	[    1.851078] note: kworker/u16:0[11] exited with irqs disabled
	[    1.855791] note: kworker/u16:0[11] exited with preempt_count 1
	[    1.861586] ------------[ cut here ]------------

Randomly, the following call seems to return -EBUSY causing
the above BUG().

	ret = __cpufreq_driver_target(policy, old_freq - 1,
				      CPUFREQ_RELATION_L);

	/*
	 * Reaching here after boot in a few seconds may not
	 * mean that system will remain stable at "unknown"
	 * frequency for longer duration. Hence, a BUG_ON().
	 */
	BUG_ON(ret);

Not sure why this does not happen in every boot, and how it
is tied to genpd_names. Will debug and update.

Thanks
Varada

> >  };
> >
> >  static const struct qcom_cpufreq_match_data match_data_krait = {
> > --
> > 2.34.1
> >
>
> --
> With best wishes
> Dmitry

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