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From:   Pi-Hsun Shih <pihsun@chromium.org>
Date:   Thu, 13 Jun 2019 16:20:03 +0800
Message-ID: <CANdKZ0emRPcTcL7Yq5nLH5z2_9fBuuczKehA8oEi0b+je15RPg@mail.gmail.com>
Subject: Re: [PATCH v7 16/21] memory: mtk-smi: Add bus_sel for mt8183
To:     Yong Wu <yong.wu@mediatek.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Rob Herring <robh+dt@kernel.org>,
        Evan Green <evgreen@chromium.org>,
        Tomasz Figa <tfiga@google.com>,
        Will Deacon <will.deacon@arm.com>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>, srv_heupstream@mediatek.com,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@lists.infradead.org>,
        iommu@lists.linux-foundation.org, yingjoe.chen@mediatek.com,
        youlin.pei@mediatek.com, Nicolas Boichat <drinkcat@chromium.org>,
        anan.sun@mediatek.com, Matthias Kaehlcke <mka@chromium.org>
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(Sorry for the possibly double-posting, my last mail got rejected by
some mailing lists.)

Hi,
When I tested this patch series (Based on linux 5.2.0-rc2, and with
various other patch series about MT8183) with lockdep enabled, and I'm
seeing the following lockdep warning on boot.

By bisecting the commits, the first commit that introduce this warning
is this patch. The warning also doesn't appear if
https://lore.kernel.org/patchwork/patch/1086582/ and
https://lore.kernel.org/patchwork/patch/1086583/ are not applied.

Do anyone have idea on why this is happening, or any suggestion on
which part I should be digging into to figure this out? Thanks.

[    4.664194] ======================================================
[    4.670368] WARNING: possible circular locking dependency detected
[    4.676545] 5.2.0-rc2-next-20190528-44527-g6c94b6475c04 #20 Tainted: G S
[    4.684539] ------------------------------------------------------
[    4.690714] kworker/4:1/51 is trying to acquire lock:
[    4.695760] (____ptrval____) (regulator_list_mutex){+.+.},
at:regulator_lock_dependent+0xdc/0x6c4
[    4.704732]
[    4.704732] but task is already holding lock:
[    4.710556] (____ptrval____) (&genpd->mlock/1){+.+.},
at:genpd_lock_nested_mtx+0x24/0x30
[    4.718740]
[    4.718740] which lock already depends on the new lock.
[    4.718740]
[    4.726908]
[    4.726908] the existing dependency chain (in reverse order) is:
[    4.734382]
[    4.734382] -> #4 (&genpd->mlock/1){+.+.}:
[    4.739963]        __mutex_lock_common+0x1a0/0x1fe8
[    4.744836]        mutex_lock_nested+0x40/0x50
[    4.749275]        genpd_lock_nested_mtx+0x24/0x30
[    4.754063]        genpd_add_subdomain+0x150/0x524
[    4.758850]        pm_genpd_add_subdomain+0x3c/0x5c
[    4.763723]        scpsys_probe+0x520/0xe78
[    4.767902]        platform_drv_probe+0xf4/0x134
[    4.772517]        really_probe+0x214/0x4dc
[    4.776696]        driver_probe_device+0xcc/0x1d4
[    4.781396]        __device_attach_driver+0x10c/0x180
[    4.786442]        bus_for_each_drv+0x124/0x184
[    4.790968]        __device_attach+0x1c0/0x2d8
[    4.795407]        device_initial_probe+0x20/0x2c
[    4.800106]        bus_probe_device+0x80/0x16c
[    4.804546]        deferred_probe_work_func+0x120/0x168
[    4.809767]        process_one_work+0x858/0x1208
[    4.814379]        worker_thread+0x9ec/0xcb8
[    4.818644]        kthread+0x2b8/0x2d0
[    4.822391]        ret_from_fork+0x10/0x18
[    4.826480]
[    4.826480] -> #3 (&genpd->mlock){+.+.}:
[    4.831880]        __mutex_lock_common+0x1a0/0x1fe8
[    4.836752]        mutex_lock_nested+0x40/0x50
[    4.841190]        genpd_lock_mtx+0x20/0x2c
[    4.845369]        genpd_runtime_resume+0x140/0x434
[    4.850241]        __rpm_callback+0xb0/0x1e4
[    4.854506]        rpm_callback+0x54/0x1a8
[    4.858597]        rpm_resume+0xc6c/0x10c4
[    4.862689]        __pm_runtime_resume+0xb4/0x124
[    4.867387]        device_link_add+0x598/0x8d0
[    4.871829]        mtk_smi_larb_probe+0x2b0/0x340
[    4.876528]        platform_drv_probe+0xf4/0x134
[    4.881141]        really_probe+0x214/0x4dc
[    4.885320]        driver_probe_device+0xcc/0x1d4
[    4.890020]        __device_attach_driver+0x10c/0x180
[    4.895066]        bus_for_each_drv+0x124/0x184
[    4.899591]        __device_attach+0x1c0/0x2d8
[    4.904031]        device_initial_probe+0x20/0x2c
[    4.908730]        bus_probe_device+0x80/0x16c
[    4.913169]        deferred_probe_work_func+0x120/0x168
[    4.918387]        process_one_work+0x858/0x1208
[    4.923000]        worker_thread+0x9ec/0xcb8
[    4.927264]        kthread+0x2b8/0x2d0
[    4.931009]        ret_from_fork+0x10/0x18
[    4.935098]
[    4.935098] -> #2 (dpm_list_mtx){+.+.}:
[    4.940412]        __mutex_lock_common+0x1a0/0x1fe8
[    4.945284]        mutex_lock_nested+0x40/0x50
[    4.949722]        device_pm_lock+0x1c/0x24
[    4.953900]        device_link_add+0x98/0x8d0
[    4.958252]        _regulator_get+0x3f0/0x504
[    4.962606]        _devm_regulator_get+0x58/0xb8
[    4.967218]        devm_regulator_get+0x28/0x34
[    4.971746]        pwm_backlight_probe+0x61c/0x1b90
[    4.976617]        platform_drv_probe+0xf4/0x134
[    4.981230]        really_probe+0x214/0x4dc
[    4.985409]        driver_probe_device+0xcc/0x1d4
[    4.990108]        device_driver_attach+0xe4/0x104
[    4.994894]        __driver_attach+0x134/0x14c
[    4.999333]        bus_for_each_dev+0x120/0x180
[    5.003859]        driver_attach+0x48/0x54
[    5.007950]        bus_add_driver+0x2ac/0x44c
[    5.012303]        driver_register+0x160/0x288
[    5.016742]        __platform_driver_register+0xcc/0xdc
[    5.021964]        pwm_backlight_driver_init+0x1c/0x24
[    5.027097]        do_one_initcall+0x38c/0x994
[    5.031536]        do_initcall_level+0x3a4/0x4b8
[    5.036148]        do_basic_setup+0x84/0xa0
[    5.036153]        kernel_init_freeable+0x23c/0x324
[    5.036158]        kernel_init+0x14/0x110
[    5.036164]        ret_from_fork+0x10/0x18
[    5.036166]
[    5.036166] -> #1 (device_links_lock){+.+.}:
[    5.065905]        __mutex_lock_common+0x1a0/0x1fe8
[    5.070777]        mutex_lock_nested+0x40/0x50
[    5.075215]        device_link_remove+0x40/0xe0
[    5.079740]        _regulator_put+0x104/0x2d8
[    5.084093]        regulator_put+0x30/0x44
[    5.088184]        devm_regulator_release+0x38/0x44
[    5.093056]        release_nodes+0x604/0x670
[    5.097320]        devres_release_all+0x70/0x8c
[    5.101846]        really_probe+0x270/0x4dc
[    5.106024]        driver_probe_device+0xcc/0x1d4
[    5.110724]        device_driver_attach+0xe4/0x104
[    5.115510]        __driver_attach+0x134/0x14c
[    5.119949]        bus_for_each_dev+0x120/0x180
[    5.124474]        driver_attach+0x48/0x54
[    5.128566]        bus_add_driver+0x2ac/0x44c
[    5.132919]        driver_register+0x160/0x288
[    5.137357]        __platform_driver_register+0xcc/0xdc
[    5.142576]        pwm_backlight_driver_init+0x1c/0x24
[    5.147708]        do_one_initcall+0x38c/0x994
[    5.152146]        do_initcall_level+0x3a4/0x4b8
[    5.156758]        do_basic_setup+0x84/0xa0
[    5.160936]        kernel_init_freeable+0x23c/0x324
[    5.165807]        kernel_init+0x14/0x110
[    5.169813]        ret_from_fork+0x10/0x18
[    5.173901]
[    5.173901] -> #0 (regulator_list_mutex){+.+.}:
[    5.179910]        lock_acquire+0x350/0x4d4
[    5.184088]        __mutex_lock_common+0x1a0/0x1fe8
[    5.184095]        mutex_lock_nested+0x40/0x50
[    5.197475]        regulator_lock_dependent+0xdc/0x6c4
[    5.197482]        regulator_disable+0xa0/0x138
[    5.197487]        scpsys_power_off+0x38c/0x4bc
[    5.197495]        genpd_power_off+0x3d8/0x6a0
[    5.209399]        genpd_power_off+0x530/0x6a0
[    5.209406]        genpd_power_off_work_fn+0x74/0xc0
[    5.209411]        process_one_work+0x858/0x1208
[    5.209419]        worker_thread+0x9ec/0xcb8
[    5.219067]        kthread+0x2b8/0x2d0
[    5.219073]        ret_from_fork+0x10/0x18
[    5.219077]
[    5.219077] other info that might help us debug this:
[    5.219077]
[    5.219080] Chain exists of:
[    5.219080]   regulator_list_mutex --> &genpd->mlock --> &genpd->mlock/1
[    5.219080]
[    5.228039]  Possible unsafe locking scenario:
[    5.228039]
[    5.228042]        CPU0                    CPU1
[    5.228046]        ----                    ----
[    5.228048]   lock(&genpd->mlock/1);
[    5.228058]                                lock(&genpd->mlock);
[    5.311647]                                lock(&genpd->mlock/1);
[    5.317736]   lock(regulator_list_mutex);
[    5.321742]
[    5.321742]  *** DEADLOCK ***
[    5.321742]
[    5.327655] 4 locks held by kworker/4:1/51:
[    5.331831]  #0: (____ptrval____) ((wq_completion)pm){+.+.},
at:process_one_work+0x57c/0x1208
[    5.340444]  #1: (____ptrval____)
((work_completion)(&genpd->power_off_work)){+.+.},
at:process_one_work+0x5b8/0x1208
[    5.351139]  #2: (____ptrval____) (&genpd->mlock){+.+.},
at:genpd_lock_mtx+0x20/0x2c
[    5.358970]  #3: (____ptrval____) (&genpd->mlock/1){+.+.},
at:genpd_lock_nested_mtx+0x24/0x30
[    5.367584]
[    5.367584] stack backtrace:
[    5.371939] CPU: 4 PID: 51 Comm: kworker/4:1 Tainted: G S
     5.2.0-rc2-next-20190528-44527-g6c94b6475c04 #20
[    5.382809] Workqueue: pm genpd_power_off_work_fn
[    5.382816] Call trace:
[    5.382822]  dump_backtrace+0x0/0x2c0
[    5.382830]  show_stack+0x20/0x2c
[    5.409174]  dump_stack+0x10c/0x17c
[    5.412659]  print_circular_bug+0x42c/0x4d0
[    5.416838]  __lock_acquire+0x4c88/0x5484
[    5.420843]  lock_acquire+0x350/0x4d4
[    5.424500]  __mutex_lock_common+0x1a0/0x1fe8
[    5.428851]  mutex_lock_nested+0x40/0x50
[    5.432770]  regulator_lock_dependent+0xdc/0x6c4
[    5.437383]  regulator_disable+0xa0/0x138
[    5.441389]  scpsys_power_off+0x38c/0x4bc
[    5.445393]  genpd_power_off+0x3d8/0x6a0
[    5.449310]  genpd_power_off+0x530/0x6a0
[    5.453229]  genpd_power_off_work_fn+0x74/0xc0
[    5.457667]  process_one_work+0x858/0x1208
[    5.461758]  worker_thread+0x9ec/0xcb8
[    5.465503]  kthread+0x2b8/0x2d0
[    5.468727]  ret_from_fork+0x10/0x18

On Mon, Jun 10, 2019 at 8:21 PM Yong Wu <yong.wu@mediatek.com> wrote:
> ...
> +       } else {
> +               res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +               common->base = devm_ioremap_resource(dev, res);
> +               if (IS_ERR(common->base))
> +                       return PTR_ERR(common->base);
>         }
>         pm_runtime_enable(dev);
>         platform_set_drvdata(pdev, common);