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.