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Date:   Thu, 3 Dec 2020 09:47:39 +0000
From:   Mark Brown <broonie@kernel.org>
To:     "Ardelean, Alexandru" <alexandru.Ardelean@analog.com>
Cc:     Andy Shevchenko <andy.shevchenko@gmail.com>,
        linux-spi <linux-spi@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        "Bogdan, Dragos" <Dragos.Bogdan@analog.com>
Subject: Re: [PATCH v3 2/3] spi: Add SPI_NO_TX/RX support
Message-ID: <20201203094739.GB4700@sirena.org.uk>
References: <20201127130834.136348-1-alexandru.ardelean@analog.com>
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On Thu, Dec 03, 2020 at 08:20:57AM +0000, Ardelean, Alexandru wrote:

> > > > @@ -43,5 +43,7 @@
> > > >  #define        SPI_TX_OCTAL            0x2000          /* transmit with 8 wires */
> > > >  #define        SPI_RX_OCTAL            0x4000          /* receive with 8 wires */
> > > >  #define        SPI_3WIRE_HIZ           0x8000          /* high impedance turnaround
> > */
> > > > +#define        SPI_NO_TX               0x10000         /* no transmit wire */
> > > > +#define        SPI_NO_RX               0x20000         /* no receive wire */

> > > Is it really material for uAPI?
> > > Perhaps we may have something like
> > > SPI_MODE_USER_MASK in uAPI and
> > > in internal headers

> Hmm, in a way this could make sense for some SPIDEVs as well, to set these flags and get an error if they try to TX with the NO_TX flag set.
> Not really sure about this.
> Initially I mechanically added these here as an inertia to the previous patch which is just unifying the headers.

> Any other opinions? Thoughts?
> Mark?

spidev is hacky at the best of times...  It *is* probably better to only
have the usefully mainpulable modes exposed in uapi and then define the
rest internally though.

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