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From: MyungJoo Ham <myungjoo.ham@samsung.com>
To: Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"heiko@sntech.de" <heiko@sntech.de>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"dbasehore@chromium.org" <dbasehore@chromium.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"dianders@google.com" <dianders@google.com>,
	"groek@google.com" <groek@google.com>,
	"kernel@collabora.com" <kernel@collabora.com>,
	Lin Huang <hl@rock-chips.com>,
	Elaine Zhang <zhangqing@rock-chips.com>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	"linux-rockchip@lists.infradead.org"
	<linux-rockchip@lists.infradead.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Jeffy Chen <jeffy.chen@rock-chips.com>,
	Ulf Hansson <ulf.hansson@linaro.org>
Subject: RE: [PATCH 6/6] devfreq: rk3399_dmc: register devfreq notification to dmc driver.
Date: Tue, 24 Apr 2018 13:22:33 +0900	[thread overview]
Message-ID: <20180424042233epcms1p7b27cb007b11ed467d773ce93d8bc7ed4@epcms1p7> (raw)
In-Reply-To: <20180419104019.24406-7-enric.balletbo@collabora.com>

>From: Lin Huang <hl@rock-chips.com>
>
>Because dmc may also access the PMU_BUS_IDLE_REQ register, we need to
>ensure that the pd driver and the dmc driver will not access at this
>register at the same time.
>
>Signed-off-by: Lin Huang <hl@rock-chips.com>
>Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
>---
>
> drivers/devfreq/rk3399_dmc.c      | 47 +----------------------
> drivers/soc/rockchip/pm_domains.c | 31 +++++++++++++++
> include/soc/rockchip/rk3399_dmc.h | 63 +++++++++++++++++++++++++++++++
> 3 files changed, 96 insertions(+), 45 deletions(-)
> create mode 100644 include/soc/rockchip/rk3399_dmc.h
>
>diff --git a/drivers/devfreq/rk3399_dmc.c b/drivers/devfreq/rk3399_dmc.c
>index 5bfca028eaaf..a1f320634d69 100644
>--- a/drivers/devfreq/rk3399_dmc.c
>+++ b/drivers/devfreq/rk3399_dmc.c
[]
>diff --git a/drivers/soc/rockchip/pm_domains.c b/drivers/soc/rockchip/pm_domains.c
>index 53efc386b1ad..7acc836e7eb7 100644
>--- a/drivers/soc/rockchip/pm_domains.c
>+++ b/drivers/soc/rockchip/pm_domains.c
[]
>+static int dmc_notify(struct notifier_block *nb, unsigned long event,
>+		      void *data)
>+{
>+	if (event == DEVFREQ_PRECHANGE)
>+		mutex_lock(&dmc_pmu->mutex);
>+	else if (event == DEVFREQ_POSTCHANGE)
>+		mutex_unlock(&dmc_pmu->mutex);
>+
>+	return NOTIFY_OK;
>+}
>+

Doesn't this incur a deadlock?

1. devfreq.c:update_freq calls devfreq_notify_transition(DEVFREQ_PRECHANGE)
2. pm_domain.c:dmc_notify calls mutex_lock(dmc_pmu->mutex)
3. devfreq.c:update_freq calls target callback
4. rk3399_dmc.c:rk3399_dmcfreq_target calls mutex_lock(&dmcfreq->lock)
   >>>>>> update_freq cannot proceed. <<<<


Cheers,
MyungJoo

  parent reply	other threads:[~2018-04-24  4:22 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-19 10:40 [PATCH 0/6] devfreq: rk3399_dmc: improve rk3399_dmc driver and it's documentation Enric Balletbo i Serra
2018-04-19 10:40 ` [PATCH 1/6] dt-bindings: devfreq: rk3399_dmc: improve binding documentation Enric Balletbo i Serra
2018-04-19 10:40 ` [PATCH 2/6] dt-bindings: clock: add DDR3 standard speed bins Enric Balletbo i Serra
2018-04-19 11:10   ` Heiko Stuebner
2018-04-19 11:30     ` Enric Balletbo i Serra
2018-04-20 10:58       ` Heiko Stuebner
2018-04-19 10:40 ` [PATCH 3/6] devfreq: rk3399_dmc: remove wait for dcf irq event Enric Balletbo i Serra
2018-04-24  3:55   ` Chanwoo Choi
2018-04-19 10:40 ` [PATCH 4/6] dt-bindings: devfreq: rk3399_dmc: remove interrupts as is not required Enric Balletbo i Serra
2018-04-24  3:56   ` Chanwoo Choi
2018-04-19 10:40 ` [PATCH 5/6] devfreq: rk3399_dmc: do not print error when get supply and clk defer Enric Balletbo i Serra
2018-04-23 10:44   ` Ulf Hansson
2018-04-23 13:37     ` Ezequiel Garcia
2018-04-24  3:55   ` Chanwoo Choi
2018-04-19 10:40 ` [PATCH 6/6] devfreq: rk3399_dmc: register devfreq notification to dmc driver Enric Balletbo i Serra
2018-04-24  4:08   ` Chanwoo Choi
2018-04-23 10:53 ` [PATCH 0/6] devfreq: rk3399_dmc: improve rk3399_dmc driver and it's documentation Ulf Hansson
     [not found] ` <CGME20180419104054epcas5p49612174afb26493bcd937a0232b9b1df@epcms1p3>
2018-04-24  1:53   ` [PATCH 1/6] dt-bindings: devfreq: rk3399_dmc: improve binding documentation MyungJoo Ham
     [not found] ` <CGME20180419104056epcas2p29c74949b650fea596900e395dec662e8@epcms1p7>
2018-04-24  2:31   ` [PATCH 3/6] devfreq: rk3399_dmc: remove wait for dcf irq event MyungJoo Ham
     [not found] ` <CGME20180419104057epcas5p311ecfdeb6cb535cd7100232d282ac323@epcms1p4>
2018-04-24  2:33   ` [PATCH 5/6] devfreq: rk3399_dmc: do not print error when get supply and clk defer MyungJoo Ham
     [not found] ` <CGME20180419104059epcas2p3fe5aba95859e02307556200a42bc1ac2@epcms1p7>
2018-04-24  4:22   ` MyungJoo Ham [this message]
2018-04-24  8:01     ` [PATCH 6/6] devfreq: rk3399_dmc: register devfreq notification to dmc driver Enric Balletbo i Serra

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