>From: Lin Huang <hl@xxxxxxxxxxxxxx>
>
>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@xxxxxxxxxxxxxx>
>Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
>---
>
> 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
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