Re: [PATCH v7 16/21] memory: mtk-smi: Add bus_sel for mt8183

[Pi-Hsun Shih]

On Thu, Jun 20, 2019 at 7:38 PM Matthias Brugger <matthias.bgg@xxxxxxxxx> wrote:
>
> CCing Sascha
>
> On 20/06/2019 11:35, Matthias Brugger wrote:
> >
> >
> > On 13/06/2019 10:14, Pi-Hsun Shih wrote:
> >> 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
> >
> > For this looks as if you have also patch
> > [PATCH v2 04/12] memory: mtk-smi: Add device-link between smi-larb and smi-common
> > from series
> > [PATCH v2 00/12] Clean up "mediatek,larb" after adding device_link
> > applied.
> >
>
> My guess is, that we run into this, because we call genpd_runtime_resume before
> we have finished the subdomain registration in scpsys_probe.
> That implies that you also have the scpsys series for mt8183 added to your tree.
>
> Anyway it looks to me as if we have to add the subdomains before we call
> of_genpd_add_provider_onecell().
>
> Regards,
> Matthias

Yes I do have scpsys series for mt8183 added in my tree. (I have about
125 patches from list on top of 531b0a360899 "Add linux-next specific
files for 20190528" to make the board boot)
However the exact same warning still exists after I changed the order
of of_genpd_add_provider_onecell and pm_genpd_add_subdomain, patch as
follow:
(Patch is based on commit f4788d37bc84 "Add linux-next specific files
for 20190614")

diff --git a/drivers/soc/mediatek/mtk-scpsys.c
b/drivers/soc/mediatek/mtk-scpsys.c
index 503222d0d0da..0cd9bdd4004e 100644
--- a/drivers/soc/mediatek/mtk-scpsys.c
+++ b/drivers/soc/mediatek/mtk-scpsys.c
@@ -440,8 +440,7 @@ static struct scp *init_scp(struct platform_device *pdev,
 static void mtk_register_power_domains(struct platform_device *pdev,
  struct scp *scp, int num)
 {
- struct genpd_onecell_data *pd_data;
- int i, ret;
+ int i;

  for (i = 0; i < num; i++) {
  struct scp_domain *scpd = &scp->domains[i];
@@ -457,18 +456,6 @@ static void mtk_register_power_domains(struct
platform_device *pdev,

  pm_genpd_init(genpd, NULL, false);
  }
-
- /*
- * We are not allowed to fail here since there is no way to unregister
- * a power domain. Once registered above we have to keep the domains
- * valid.
- */
-
- pd_data = &scp->pd_data;
-
- ret = of_genpd_add_provider_onecell(pdev->dev.of_node, pd_data);
- if (ret)
- dev_err(&pdev->dev, "Failed to add OF provider: %d\n", ret);
 }

 /*
@@ -1053,6 +1040,16 @@ static int scpsys_probe(struct platform_device *pdev)
  ret);
  }

+ /*
+ * We are not allowed to fail here since there is no way to unregister
+ * a power domain. Once registered above we have to keep the domains
+ * valid.
+ */
+
+ ret = of_genpd_add_provider_onecell(pdev->dev.of_node, pd_data);
+ if (ret)
+ dev_err(&pdev->dev, "Failed to add OF provider: %d\n", ret);
+
  return 0;
 }

>
>
> > Regards,
> > Matthias
> >