linux-kernel - Re: [PATCH v3 15/16] soc: mediatek: pm-domains: Add default power off flag

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Date:   Thu, 29 Oct 2020 15:51:55 +0100
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     Weiyi Lu <weiyi.lu@...iatek.com>
Cc:     Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        linux-kernel@...r.kernel.org, drinkcat@...omium.org,
        hsinyi@...omium.org, Collabora Kernel ML <kernel@...labora.com>,
        fparent@...libre.com, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v3 15/16] soc: mediatek: pm-domains: Add default power off
 flag



On 27/10/2020 12:18, Weiyi Lu wrote:
> On Tue, 2020-10-27 at 11:53 +0100, Matthias Brugger wrote:
>>
>> On 26/10/2020 18:55, Enric Balletbo i Serra wrote:
>>> From: Weiyi Lu <weiyi.lu@...iatek.com>
>>>
>>> For some power domain, like conn on MT8192, it should be default OFF.
>>> Because the power on/off control relies the function of connectivity chip
>>> and its firmware. And if project choose other chip vendor solution,
>>> those necessary connectivity functions will not provided.
>>>
>>> Signed-off-by: Weiyi Lu <weiyi.lu@...iatek.com>
>>> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
>>> ---
>>>
>>> Changes in v3: None
>>> Changes in v2: None
>>>
>>>    drivers/soc/mediatek/mtk-pm-domains.c | 23 +++++++++++++++++------
>>>    drivers/soc/mediatek/mtk-pm-domains.h |  1 +
>>>    2 files changed, 18 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/soc/mediatek/mtk-pm-domains.c b/drivers/soc/mediatek/mtk-pm-domains.c
>>> index 63993076a544..fe0e955076a0 100644
>>> --- a/drivers/soc/mediatek/mtk-pm-domains.c
>>> +++ b/drivers/soc/mediatek/mtk-pm-domains.c
>>> @@ -378,10 +378,16 @@ generic_pm_domain *scpsys_add_one_domain(struct scpsys *scpsys, struct device_no
>>>    	 * software.  The unused domains will be switched off during
>>>    	 * late_init time.
>>>    	 */
>>> -	ret = scpsys_power_on(&pd->genpd);
>>> -	if (ret < 0) {
>>> -		dev_err(scpsys->dev, "%pOF: failed to power on domain: %d\n", node, ret);
>>> -		goto err_unprepare_clocks;
>>> +	if (MTK_SCPD_CAPS(pd, MTK_SCPD_KEEP_DEFAULT_OFF)) {
>>> +		if (scpsys_domain_is_on(pd))
>>> +			dev_warn(scpsys->dev,
>>> +				 "%pOF: A default off power domain has been ON\n", node);
>>> +	} else {
>>> +		ret = scpsys_power_on(&pd->genpd);
>>> +		if (ret < 0) {
>>> +			dev_err(scpsys->dev, "%pOF: failed to power on domain: %d\n", node, ret);
>>> +			goto err_unprepare_clocks;
>>> +		}
>>>    	}
>>>    
>>>    	if (scpsys->domains[id]) {
>>> @@ -395,7 +401,11 @@ generic_pm_domain *scpsys_add_one_domain(struct scpsys *scpsys, struct device_no
>>>    	pd->genpd.power_off = scpsys_power_off;
>>>    	pd->genpd.power_on = scpsys_power_on;
>>>    
>>> -	pm_genpd_init(&pd->genpd, NULL, false);
>>> +	if (MTK_SCPD_CAPS(pd, MTK_SCPD_KEEP_DEFAULT_OFF))
>>> +		pm_genpd_init(&pd->genpd, NULL, true);
>>> +	else
>>> +		pm_genpd_init(&pd->genpd, NULL, false);
>>> +
>>>    	scpsys->domains[id] = &pd->genpd;
>>>    
>>>    	return scpsys->pd_data.domains[id];
>>> @@ -478,7 +488,8 @@ static void scpsys_remove_one_domain(struct scpsys_domain *pd)
>>>    			"failed to remove domain '%s' : %d - state may be inconsistent\n",
>>>    			pd->genpd.name, ret);
>>>    
>>> -	scpsys_power_off(&pd->genpd);
>>> +	if (!MTK_SCPD_CAPS(pd, MTK_SCPD_KEEP_DEFAULT_OFF))
>>> +		scpsys_power_off(&pd->genpd);
>>
>> OK, so you merged Weiyi's patches in this series :)
>>
>> So same comment here: Does it really hurt if we turn-off a already turned-off
>> power domain? Or can we get rid of this check?
>>
> 
> We do need this check here. If you try to turn-off this power domain,
> you might make the clock or regulator reference count unbalanced.
> 

Correct. Could we check via scpsys_domain_is_on() instead? I'd like to avoid 
MTK_SCPD_KEEP_DEFAULT_OFF use here.

Regards,
Matthias

>> Regards,
>> Matthias
>>
>>>    
>>>    	clk_bulk_unprepare(pd->num_clks, pd->clks);
>>>    	clk_bulk_put(pd->num_clks, pd->clks);
>>> diff --git a/drivers/soc/mediatek/mtk-pm-domains.h b/drivers/soc/mediatek/mtk-pm-domains.h
>>> index 2ad213be84a5..0fa6a938b40c 100644
>>> --- a/drivers/soc/mediatek/mtk-pm-domains.h
>>> +++ b/drivers/soc/mediatek/mtk-pm-domains.h
>>> @@ -6,6 +6,7 @@
>>>    #define MTK_SCPD_ACTIVE_WAKEUP		BIT(0)
>>>    #define MTK_SCPD_FWAIT_SRAM		BIT(1)
>>>    #define MTK_SCPD_SRAM_ISO		BIT(2)
>>> +#define MTK_SCPD_KEEP_DEFAULT_OFF	BIT(3)
>>>    #define MTK_SCPD_CAPS(_scpd, _x)	((_scpd)->data->caps & (_x))
>>>    
>>>    #define SPM_VDE_PWR_CON			0x0210
>>>
>