linux-kernel - Re: [PATCH v16 3/7] soc: mediatek: SVS: introduce MTK SVS engine

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Message-ID: <7a7a07adedf5d3f430fecf81aed35c6321e5b634.camel@mediatek.com>
Date:   Fri, 14 May 2021 11:10:13 +0800
From:   Roger Lu <roger.lu@...iatek.com>
To:     Guenter Roeck <linux@...ck-us.net>
CC:     Matthias Brugger <matthias.bgg@...il.com>,
        Enric Balletbo Serra <eballetbo@...il.com>,
        Kevin Hilman <khilman@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Nicolas Boichat <drinkcat@...gle.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Fan Chen <fan.chen@...iatek.com>,
        HenryC Chen <HenryC.Chen@...iatek.com>,
        YT Lee <yt.lee@...iatek.com>,
        Xiaoqing Liu <Xiaoqing.Liu@...iatek.com>,
        "Charles Yang" <Charles.Yang@...iatek.com>,
        Angus Lin <Angus.Lin@...iatek.com>,
        "Mark Rutland" <mark.rutland@....com>, Nishanth Menon <nm@...com>,
        <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v16 3/7] soc: mediatek: SVS: introduce MTK SVS engine

Hi Guenter,

Sorry for the late reply and thanks for the notice.

On Wed, 2021-05-05 at 21:51 -0700, Guenter Roeck wrote:
> On Wed, Apr 28, 2021 at 02:54:36PM +0800, Roger Lu wrote:
> > The Smart Voltage Scaling(SVS) engine is a piece of hardware
> > which calculates suitable SVS bank voltages to OPP voltage table.
> > Then, DVFS driver could apply those SVS bank voltages to PMIC/Buck
> > when receiving OPP_EVENT_ADJUST_VOLTAGE.
> > 
> > Signed-off-by: Roger Lu <roger.lu@...iatek.com>
> > ---
> >  drivers/soc/mediatek/Kconfig   |   10 +
> >  drivers/soc/mediatek/Makefile  |    1 +
> >  drivers/soc/mediatek/mtk-svs.c | 1723
> > ++++++++++++++++++++++++++++++++
> >  3 files changed, 1734 insertions(+)
> >  create mode 100644 drivers/soc/mediatek/mtk-svs.c
> > 
> 
> [ ... ]
> 
> > +
> > +	svsp_irq = irq_of_parse_and_map(svsp->dev->of_node, 0);
> > +	ret = devm_request_threaded_irq(svsp->dev, svsp_irq, NULL,
> > svs_isr,
> > +					svsp->irqflags, svsp->name,
> > svsp);
> 
> 0-day reports:
> 
> drivers/soc/mediatek/mtk-svs.c:1663:7-32: ERROR:
> 	Threaded IRQ with no primary handler requested without
> IRQF_ONESHOT
> 
> I would be a bit concerned about this. There is no primary (hard)
> interrupt handler, meaning the hard interrupt may be re-enabled after
> the default hard interrupt handler runs. This might result in endless
> interrupts.

Oh, we add IRQF_ONESHOT in "svs_get_svs_mt8183_platform_data()" for
threaded irq. So, please kindly let us know if we need to set more
flags or any other potential risks we should be aware. Thanks in
advance.

> 
> Guenter