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Date:   Wed, 22 Jun 2022 19:45:11 +0530
From:   Viresh Kumar <viresh.kumar@linaro.org>
To:     Jon Hunter <jonathanh@nvidia.com>,
        Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
        Stephen Boyd <sboyd@kernel.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>, linux-pm@vger.kernel.org,
        Vincent Guittot <vincent.guittot@linaro.org>,
        linux-kernel@vger.kernel.org,
        "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH 5/8] OPP: Allow multiple clocks for a device
Message-ID: <20220622141511.yzg5itkdwirpavfj@vireshk-i7>
References: <cover.1654849214.git.viresh.kumar@linaro.org>
 <8b29fa207024dc295639f9ba52c28e45782e3baa.1654849214.git.viresh.kumar@linaro.org>
 <55623c12-dda3-613f-5bc9-80b3b6fec5f9@nvidia.com>
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In-Reply-To: <55623c12-dda3-613f-5bc9-80b3b6fec5f9@nvidia.com>
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On 22-06-22, 14:47, Jon Hunter wrote:
> I am seeing the following panic on -next and bisect is point to
> this commit ...
> 
> [    2.145604] 8<--- cut here ---
> [    2.145615] Unable to handle kernel NULL pointer dereference at virtual address 00000000
> [    2.145625] [00000000] *pgd=00000000
> [    2.145647] Internal error: Oops: 80000005 [#1] PREEMPT SMP ARM
> [    2.145660] Modules linked in:
> [    2.145671] CPU: 1 PID: 35 Comm: kworker/u8:1 Not tainted 5.19.0-rc3-next-20220622-gf739bc2a47f6 #1
> [    2.145688] Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
> [    2.145697] Workqueue: events_unbound deferred_probe_work_func
> [    2.145740] PC is at 0x0
> [    2.145750] LR is at _set_opp+0x194/0x380
> [    2.145779] pc : [<00000000>]    lr : [<c086b578>]    psr: 20000013
> [    2.145789] sp : f08f1c80  ip : c152cb40  fp : c264c040
> [    2.145798] r10: 00000000  r9 : c152cb40  r8 : c16f3010
> [    2.145806] r7 : c264c034  r6 : 00000000  r5 : c265d800  r4 : c264c000
> [    2.145815] r3 : 00000000  r2 : c265d800  r1 : c264c000  r0 : c16f3010
> [    2.145825] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
> [    2.145840] Control: 10c5387d  Table: 8000404a  DAC: 00000051
> [    2.145847] Register r0 information: slab kmalloc-1k start c16f3000 pointer offset 16 size 1024
> [    2.145883] Register r1 information: slab kmalloc-256 start c264c000 pointer offset 0 size 256
> [    2.145914] Register r2 information: slab kmalloc-128 start c265d800 pointer offset 0 size 128
> [    2.145942] Register r3 information: NULL pointer
> [    2.145955] Register r4 information: slab kmalloc-256 start c264c000 pointer offset 0 size 256
> [    2.145983] Register r5 information: slab kmalloc-128 start c265d800 pointer offset 0 size 128
> [    2.146012] Register r6 information: NULL pointer
> [    2.146023] Register r7 information: slab kmalloc-256 start c264c000 pointer offset 52 size 256
> [    2.146052] Register r8 information: slab kmalloc-1k start c16f3000 pointer offset 16 size 1024
> [    2.146081] Register r9 information: slab task_struct start c152cb40 pointer offset 0
> [    2.146105] Register r10 information: NULL pointer
> [    2.146116] Register r11 information: slab kmalloc-256 start c264c000 pointer offset 64 size 256
> [    2.146146] Register r12 information: slab task_struct start c152cb40 pointer offset 0
> [    2.348527] Process kworker/u8:1 (pid: 35, stack limit = 0x(ptrval))
> [    2.354896] Stack: (0xf08f1c80 to 0xf08f2000)
> [    2.359273] 1c80: 00000001 c0868db0 00000000 7a13d783 c152cb40 c264c000 c16f3010 c265d800
> [    2.367471] 1ca0: c2661c40 00000001 c2661c40 00000001 c2661c40 c086b8e8 00000000 7a13d783
> [    2.375666] 1cc0: c12ea5a0 c265d800 000f4240 c058cfcc ef7dddec 000f4240 00000000 c2661e88
> [    2.383861] 1ce0: 000f4240 000f4240 c2661e98 c068d238 00000000 c2665e00 000f4240 000f4240
> [    2.392056] 1d00: c2666258 00000000 c2666000 00000001 c2661c40 c068d15c 00000000 c2666000
> [    2.400253] 1d20: c16fd140 00000000 c16fd140 00000000 00000000 c16b78b8 c16b5e00 c068d2d8
> [    2.408450] 1d40: c16b7810 c26661d8 c2666000 c068ed98 c2663d00 c2663d00 00000000 c086914c
> [    2.416647] 1d60: c2663d00 c16b7810 c068ebec c16b7894 00000004 c0174868 00000000 c16b78b8
> [    2.424843] 1d80: c16b5e00 c0684630 c16b7810 c068ebec 00000000 00000004 c0174868 c152cb40
> [    2.433041] 1da0: c16b78b8 c0684794 c16b7810 c068ebec 00000000 c068506c 00000a00 c265e040
> [    2.441237] 1dc0: c0f5bdd4 00000004 00000000 7a13d783 00000000 c16b7810 c16b7894 00000004
> [    2.449434] 1de0: 60000013 00000000 c265e10c c265e154 00000000 c06854c4 c265e040 c16b7800
> [    2.457629] 1e00: c16b7810 c152cb40 00000000 c05e42b0 00000001 00000000 ffffffff 00000000
> [    2.465824] 1e20: c16b7810 ff8067a4 01000000 7a13d783 c16b7810 c16b7810 00000000 c12f7700
> [    2.474020] 1e40: 00000000 00000001 c1367c20 c140f00d c1405800 c067a668 c16b7810 00000000
> [    2.482214] 1e60: c12f7700 c0678280 c16b7810 c12f7700 c16b7810 00000017 00000001 c06784e4
> [    2.490411] 1e80: c13b6754 f08f1ee4 c16b7810 c0678574 c12f7700 f08f1ee4 c16b7810 c152cb40
> [    2.498609] 1ea0: 00000001 c06788bc 00000000 f08f1ee4 c0678834 c067675c c1367c20 c14b4e70
> [    2.506804] 1ec0: c1ea60b8 7a13d783 c16b7810 c16b7810 c152cb40 c16b7854 c12fa050 c067810c
> [    2.515001] 1ee0: c1400000 c16b7810 00000001 7a13d783 c16b7810 c16b7810 c12fa2f0 c12fa050
> [    2.523197] 1f00: 00000000 c0677410 c16b7810 c12fa038 c12fa038 c06778d0 c12fa06c c176a180
> [    2.531394] 1f20: c1405800 c140f000 00000000 c013dd2c c152cb40 c1405800 c1203d40 c176a180
> [    2.539592] 1f40: c1405800 c140581c c1203d40 c176a198 00000088 c1367177 c1405800 c013e2a4
> [    2.547790] 1f60: c0f07434 00000000 f08f1f7c c176f7c0 c152cb40 c013e064 c176a180 c176f640
> [    2.555984] 1f80: f0831eb4 00000000 00000000 c01459b4 c176f7c0 c01458ac 00000000 00000000
> [    2.564180] 1fa0: 00000000 00000000 00000000 c01001a8 00000000 00000000 00000000 00000000
> [    2.572373] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [    2.580569] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
> [    2.588768]  _set_opp from dev_pm_opp_set_opp+0x38/0x78
> [    2.594038]  dev_pm_opp_set_opp from tegra_pmc_core_pd_set_performance_state+0x44/0xb0
> [    2.602010]  tegra_pmc_core_pd_set_performance_state from _genpd_set_performance_state+0x180/0x1d0
> [    2.611018]  _genpd_set_performance_state from _genpd_set_performance_state+0xa4/0x1d0
> [    2.618972]  _genpd_set_performance_state from genpd_set_performance_state+0x50/0x7c
> [    2.626752]  genpd_set_performance_state from genpd_runtime_resume+0x1ac/0x25c
> [    2.634016]  genpd_runtime_resume from __rpm_callback+0x38/0x14c
> [    2.640073]  __rpm_callback from rpm_callback+0x50/0x54
> [    2.645335]  rpm_callback from rpm_resume+0x394/0x7a0
> [    2.650424]  rpm_resume from __pm_runtime_resume+0x4c/0x64
> [    2.655947]  __pm_runtime_resume from host1x_probe+0x29c/0x654
> [    2.661824]  host1x_probe from platform_probe+0x5c/0xb8
> [    2.667080]  platform_probe from really_probe+0xc8/0x2a8
> [    2.672433]  really_probe from __driver_probe_device+0x84/0xe4
> [    2.678308]  __driver_probe_device from driver_probe_device+0x30/0xd0
> [    2.684789]  driver_probe_device from __device_attach_driver+0x88/0xb4
> [    2.691350]  __device_attach_driver from bus_for_each_drv+0x54/0xb4
> [    2.697647]  bus_for_each_drv from __device_attach+0xf0/0x194
> [    2.703430]  __device_attach from bus_probe_device+0x84/0x8c
> [    2.709129]  bus_probe_device from deferred_probe_work_func+0x7c/0xa8
> [    2.715608]  deferred_probe_work_func from process_one_work+0x214/0x54c
> [    2.722269]  process_one_work from worker_thread+0x240/0x508
> [    2.727960]  worker_thread from kthread+0x108/0x124
> [    2.732872]  kthread from ret_from_fork+0x14/0x2c
> [    2.737602] Exception stack(0xf08f1fb0 to 0xf08f1ff8)
> [    2.742669] 1fa0:                                     00000000 00000000 00000000 00000000
> [    2.750865] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [    2.759061] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> [    2.765690] Code: bad PC value
> [    2.768990] ---[ end trace 0000000000000000 ]---
> 
> 
> Let me know if you have any thoughts.

Maybe I understand what's going on here now, Dmitry too reported this yesterday,
cc'd. Does below fix it for you ?

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 2c1ae1286376..a7c7f6f40a7e 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1120,9 +1120,11 @@ static int _set_opp(struct device *dev, struct opp_table *opp_table,
                }
        }

-       ret = opp_table->config_clks(dev, opp_table, opp, clk_data, scaling_down);
-       if (ret)
-               return ret;
+       if (opp_table->config_clks) {
+               ret = opp_table->config_clks(dev, opp_table, opp, clk_data, scaling_down);
+               if (ret)
+                       return ret;
+       }

        /* Scaling down? Configure required OPPs after frequency */
        if (scaling_down) {

-- 
viresh