linux-kernel - Re: [PATCH v4 04/13] media: rc: sunxi: Add RXSTA bits definition

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Message-ID: <CAJiuCceZa=WEiF8_LK+jDdiXOn1i8+z8Smr6YKCpo9_XftgueQ@mail.gmail.com>
Date:   Wed, 5 Jun 2019 14:44:06 +0200
From:   Clément Péron <peron.clem@...il.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Chen-Yu Tsai <wens@...e.org>, linux-media@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH v4 04/13] media: rc: sunxi: Add RXSTA bits definition

Hi Maxime,

On Wed, 5 Jun 2019 at 11:51, Maxime Ripard <maxime.ripard@...tlin.com> wrote:
>
> On Tue, Jun 04, 2019 at 06:29:50PM +0200, Clément Péron wrote:
> > We are using RXINT bits definition when looking at RXSTA register.
> >
> > These bits are equal but it's not really proper.
> >
> > Introduce the RXSTA bits and use them to have coherency.
> >
> > Signed-off-by: Clément Péron <peron.clem@...il.com>
> > ---
> >  drivers/media/rc/sunxi-cir.c | 18 ++++++++++++------
> >  1 file changed, 12 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/media/rc/sunxi-cir.c b/drivers/media/rc/sunxi-cir.c
> > index 0504ebfc831f..572bd2257d35 100644
> > --- a/drivers/media/rc/sunxi-cir.c
> > +++ b/drivers/media/rc/sunxi-cir.c
> > @@ -48,11 +48,11 @@
> >
> >  /* Rx Interrupt Enable */
> >  #define SUNXI_IR_RXINT_REG    0x2C
> > -/* Rx FIFO Overflow */
> > +/* Rx FIFO Overflow Interrupt Enable */
> >  #define REG_RXINT_ROI_EN             BIT(0)
> > -/* Rx Packet End */
> > +/* Rx Packet End Interrupt Enable */
> >  #define REG_RXINT_RPEI_EN            BIT(1)
> > -/* Rx FIFO Data Available */
> > +/* Rx FIFO Data Available Interrupt Enable */
> >  #define REG_RXINT_RAI_EN             BIT(4)
> >
> >  /* Rx FIFO available byte level */
> > @@ -60,6 +60,12 @@
> >
> >  /* Rx Interrupt Status */
> >  #define SUNXI_IR_RXSTA_REG    0x30
> > +/* Rx FIFO Overflow */
> > +#define REG_RXSTA_ROI                        BIT(0)
> > +/* Rx Packet End */
> > +#define REG_RXSTA_RPE                        BIT(1)
> > +/* Rx FIFO Data Available */
> > +#define REG_RXSTA_RA                 BIT(4)
>
> I'm fine with it on principle, but if the consistency needs to be
> maintained then we could just reuse the above defines

There is no comment why we can reuse them, they can also be some wrong
case for example the RXINT_DRQ_EN bit is not present in RXSTA and same
for STAT bit present in RXSTA and not present in RXINT.

I have discover and read this code a month ago and this logic is
really not obvious nor explain.

Maybe this hack could be done when we will introduce a quirks, but for
the moment I really think that it's more proper and readable to
introduce them properly.

Regards,
Clément

>
> Maxime
>
> --
> Maxime Ripard, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com