Re: [RFC PATCH 2/2] PM / devfreq: rk3399_dmc: Block PMU during transitions

From: "Heiko Stübner" <heiko@sntech.de>
To: Brian Norris <briannorris@chromium.org>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	Chanwoo Choi <cwchoi00@gmail.com>
Cc: linux-kernel@vger.kernel.org,
	Elaine Zhang <zhangqing@rock-chips.com>,
	linux-pm@vger.kernel.org, Doug Anderson <dianders@chromium.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org
Subject: Re: [RFC PATCH 2/2] PM / devfreq: rk3399_dmc: Block PMU during transitions
Date: Thu, 14 Apr 2022 00:45:14 +0200	[thread overview]
Message-ID: <3484357.R56niFO833@diego> (raw)
In-Reply-To: <8824147c-5512-a7a5-9e89-60b510111500@gmail.com>

Hi,

Am Donnerstag, 14. April 2022, 00:14:40 CEST schrieb Chanwoo Choi:
> On 22. 4. 6. 10:48, Brian Norris wrote:
> > See the previous patch ("soc: rockchip: power-domain: Manage resource
> > conflicts with firmware") for a thorough explanation of the conflicts.
> > While ARM Trusted Firmware may be modifying memory controller and
> > power-domain states, we need to block the kernel's power-domain driver.
> > 
> > If the power-domain driver is disabled, there is no resource conflict
> > and this becomes a no-op.
> > 
> > Signed-off-by: Brian Norris <briannorris@chromium.org>
> > ---
> > 
> >   drivers/devfreq/rk3399_dmc.c | 13 +++++++++++++
> >   1 file changed, 13 insertions(+)
> > 
> > diff --git a/drivers/devfreq/rk3399_dmc.c b/drivers/devfreq/rk3399_dmc.c
> > index e494d1497d60..daff40702615 100644
> > --- a/drivers/devfreq/rk3399_dmc.c
> > +++ b/drivers/devfreq/rk3399_dmc.c
> > @@ -21,6 +21,7 @@
> >   #include <linux/rwsem.h>
> >   #include <linux/suspend.h>
> >   
> > +#include <soc/rockchip/pm_domains.h>
> >   #include <soc/rockchip/rk3399_grf.h>
> >   #include <soc/rockchip/rockchip_sip.h>
> >   
> > @@ -93,6 +94,16 @@ static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,
> >   
> >   	mutex_lock(&dmcfreq->lock);
> >   
> > +	/*
> > +	 * Ensure power-domain transitions don't interfere with ARM Trusted
> > +	 * Firmware power-domain idling.
> > +	 */
> > +	err = rockchip_pmu_block();
> > +	if (err) {
> > +		dev_err(dev, "Failed to block PMU: %d\n", err);
> > +		goto out_unlock;
> > +	}
> > +
> >   	/*
> >   	 * Some idle parameters may be based on the DDR controller clock, which
> >   	 * is half of the DDR frequency.
> > @@ -198,6 +209,8 @@ static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,
> >   	dmcfreq->volt = target_volt;
> >   
> >   out:
> > +	rockchip_pmu_unblock();
> > +out_unlock:
> >   	mutex_unlock(&dmcfreq->lock);
> >   	return err;
> >   }
> 
> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>

so I guess you're ok with me picking up both patches, right?
[Just making sure :-) ]

Thanks
Heiko

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