| Message ID | 1436874064-2729-1-git-send-email-geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
Hi Geert, do you mean to test if the patch [1] solves your problem. -- Daniel [1] https://lkml.org/lkml/2015/1/16/81
Hi Daniel, On Thu, Jul 16, 2015 at 3:41 PM, Daniel Lezcano <daniel.lezcano@linaro.org> wrote: > do you mean to test if the patch [1] solves your problem. > > -- Daniel > > [1] https://lkml.org/lkml/2015/1/16/81 I'll give it a try after my holidays... Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Daniel, On Thu, Jul 16, 2015 at 4:03 PM, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > On Thu, Jul 16, 2015 at 3:41 PM, Daniel Lezcano > <daniel.lezcano@linaro.org> wrote: >> do you mean to test if the patch [1] solves your problem. >> >> -- Daniel >> >> [1] https://lkml.org/lkml/2015/1/16/81 > > I'll give it a try after my holidays... Apparently that patch was integrated in v4.2-rc1, while I still see the problem on recent kernels. Furthermore, that patch handles clockevents, not clocksources. struct clocksource doesn't seem to have a way to check if it's enabled, so I still need my patch. Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08/05/2015 03:56 PM, Geert Uytterhoeven wrote: > Hi Daniel, > > On Thu, Jul 16, 2015 at 4:03 PM, Geert Uytterhoeven > <geert@linux-m68k.org> wrote: >> On Thu, Jul 16, 2015 at 3:41 PM, Daniel Lezcano >> <daniel.lezcano@linaro.org> wrote: >>> do you mean to test if the patch [1] solves your problem. >>> >>> -- Daniel >>> >>> [1] https://lkml.org/lkml/2015/1/16/81 >> >> I'll give it a try after my holidays... > > Apparently that patch was integrated in v4.2-rc1, while I still see the problem > on recent kernels. > > Furthermore, that patch handles clockevents, not clocksources. > struct clocksource doesn't seem to have a way to check if it's enabled, > so I still need my patch. Hmm, I see. I will take this patch as a fix then. Thanks. -- Daniel
diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c index d56d4e0e3fb3956d..ef799532a7a7963e 100644 --- a/drivers/clocksource/sh_cmt.c +++ b/drivers/clocksource/sh_cmt.c @@ -661,6 +661,9 @@ static void sh_cmt_clocksource_suspend(struct clocksource *cs) { struct sh_cmt_channel *ch = cs_to_sh_cmt(cs); + if (!ch->cs_enabled) + return; + sh_cmt_stop(ch, FLAG_CLOCKSOURCE); pm_genpd_syscore_poweroff(&ch->cmt->pdev->dev); } @@ -669,6 +672,9 @@ static void sh_cmt_clocksource_resume(struct clocksource *cs) { struct sh_cmt_channel *ch = cs_to_sh_cmt(cs); + if (!ch->cs_enabled) + return; + pm_genpd_syscore_poweron(&ch->cmt->pdev->dev); sh_cmt_start(ch, FLAG_CLOCKSOURCE); }
Currently the sh_cmt clocksource timer is disabled or enabled unconditionally on clocksource suspend resp. resume, even if a better clocksource is present (e.g. arch_sys_counter) and the sh_cmt clocksource is not enabled. As sh_cmt is a syscore device when its timer is enabled, this may lead to a genpd.prepared_count imbalance in the presence of PM Domains, which may cause a lock-up during reboot after s2ram. During suspend: - pm_genpd_prepare() is called for all non-syscore devices (incl. sh_cmt), increasing genpd.prepared_count for each device, - clocksource.suspend() is called for all clocksource devices, - sh_cmt_clocksource_suspend() calls sh_cmt_stop(), which is a no-op as the clocksource was not enabled. During resume: - clocksource.resume() is called for all clocksource devices, - sh_cmt_clocksource_resume() calls sh_cmt_start(), which enables the clocksource timer, and turns sh_cmt into a syscore device, - pm_genpd_complete() is called for all non-syscore devices (excl. sh_cmt now!), decreasing genpd.prepared_count for each device but sh_cmt. Now genpd.prepared_count of the PM Domain containing sh_cmt is still 1 instead of zero. On subsequent suspend/resume cycles, sh_cmt is still a syscore device, hence it's skipped for pm_genpd_{prepare,complete}(), keeping the imbalance of genpd.prepared_count at 1. During reboot: - platform_drv_shutdown() is called for any platform device that has a driver with a .shutdown() method (only rcar-dmac on R-Car Gen2), - platform_drv_shutdown() calls dev_pm_domain_detach(), which calls genpd_dev_pm_detach(), - genpd_dev_pm_detach() keeps calling pm_genpd_remove_device() until it doesn't return -EAGAIN[*], - If the device is part of the same PM Domain as sh_cmt, pm_genpd_remove_device() always fails with -EAGAIN due to genpd.prepared_count > 0. - Infinite loop in genpd_dev_pm_detach()[*]. [*] Commit 93af5e9354432828 ("PM / Domains: Avoid infinite loops in attach/detach code") already limited the number of loop iterations, avoiding the lock-up. To fix this, only disable or enable the clocksource timer on clocksource suspend resp. resume if the clocksource was enabled. This was tested on r8a7791/koelsch with the CPG Clock Domain: - using arch_sys_counter as the clocksource, which is the default, and which showed the problem, - using sh_cmt as a clocksource ("echo ffca0000.timer > \ /sys/devices/system/clocksource/clocksource0/current_clocksource"), which behaves the same as before. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- v1 was part of "[PATCH 0/2] PM / Domains: Infinite loop during reboot" (https://lkml.org/lkml/2015/6/18/212). The other part has been applied already (commit 93af5e9354432828). v2: - Add Acked-by, - Add a reference to the commit that fixed the infinite loop in the core PM Domain code. --- drivers/clocksource/sh_cmt.c | 6 ++++++ 1 file changed, 6 insertions(+)