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

From: Chanwoo Choi <cwchoi00@gmail.com>
To: "Heiko Stübner" <heiko@sntech.de>,
	"Brian Norris" <briannorris@chromium.org>,
	"MyungJoo Ham" <myungjoo.ham@samsung.com>,
	"Kyungmin Park" <kyungmin.park@samsung.com>,
	"Chanwoo Choi" <cw00.choi@samsung.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 08:13:32 +0900	[thread overview]
Message-ID: <582e3645-b24e-356e-7f0f-0d37bb1e32e6@gmail.com> (raw)
In-Reply-To: <3484357.R56niFO833@diego>

On 22. 4. 14. 07:45, Heiko Stübner wrote:
> 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 :-) ]

This patch have the dependency of latest devfreq-next branch.
So that need to make the immutable branch between rockchip and devfreq.

-- 
Best Regards,
Samsung Electronics
Chanwoo Choi

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