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From:   =?UTF-8?B?6YOt5Yqb6LGq?= <lhjeff911@gmail.com>
Date:   Thu, 14 Apr 2022 21:16:15 +0800
Message-ID: <CAGcXWkzZex-XTEoq8H5mc+3Y2BH=cphdpH-815Y+TAq812K=8g@mail.gmail.com>
Subject: Re: [PATCH] spi: remove spin_lock_irq in the irq procress
To:     Tom Rix <trix@redhat.com>
Cc:     Mark Brown <broonie@kernel.org>, linux-spi@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        =?UTF-8?B?5ZGC6Iqz6aiwTHVXZWxscw==?= <wells.lu@sunplus.com>,
        "lh.kuo" <lh.kuo@sunplus.com>, nathan@kernel.org
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Hi Tom :

    This SPI driver only handles one transfer at a time.
That's why locks are not needed.


Li-hao Kuo

Tom Rix <trix@redhat.com> =E6=96=BC 2022=E5=B9=B44=E6=9C=8813=E6=97=A5 =E9=
=80=B1=E4=B8=89 =E4=B8=8B=E5=8D=887:45=E5=AF=AB=E9=81=93=EF=BC=9A
>
>
> On 4/12/22 6:38 PM, Li-hao Kuo wrote:
> > - remove spin_lock_irq and spin_unlock_irq in the irq funciton
>
> function
>
> I was expecting a statement on why is the lock is not needed.
>
> Could you add one ?
>
> Tom
>
> >
> > Signed-off-by: Li-hao Kuo <lhjeff911@gmail.com>
> > ---
> >   drivers/spi/spi-sunplus-sp7021.c | 4 +---
> >   1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/spi/spi-sunplus-sp7021.c b/drivers/spi/spi-sunplus=
-sp7021.c
> > index f989f7b..120623c 100644
> > --- a/drivers/spi/spi-sunplus-sp7021.c
> > +++ b/drivers/spi/spi-sunplus-sp7021.c
> > @@ -199,8 +199,6 @@ static irqreturn_t sp7021_spi_master_irq(int irq, v=
oid *dev)
> >       if (tx_len =3D=3D 0 && total_len =3D=3D 0)
> >               return IRQ_NONE;
> >
> > -     spin_lock_irq(&pspim->lock);
> > -
> >       rx_cnt =3D FIELD_GET(SP7021_RX_CNT_MASK, fd_status);
> >       if (fd_status & SP7021_RX_FULL_FLAG)
> >               rx_cnt =3D pspim->data_unit;
> > @@ -239,7 +237,7 @@ static irqreturn_t sp7021_spi_master_irq(int irq, v=
oid *dev)
> >
> >       if (isrdone)
> >               complete(&pspim->isr_done);
> > -     spin_unlock_irq(&pspim->lock);
> > +
> >       return IRQ_HANDLED;
> >   }
> >
>