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

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Date:   Tue, 27 Oct 2020 19:18:37 +0800
From:   Weiyi Lu <weiyi.lu@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Matthias Brugger <matthias.bgg@...il.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>,
        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>,
        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>,
        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>,
        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>,
        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 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.

> 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
> >