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Date: Mon, 29 Jul 2013 14:56:26 +0200
From: Matthieu CASTET <matthieu.castet@parrot.com>
To: wangyuhang <wangyuhang2014@gmail.com>
Subject: Re: [PATCH] SPI: DUAL and QUAD support
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Le Mon, 29 Jul 2013 11:53:14 +0100,
wangyuhang <wangyuhang2014@gmail.com> a =E9crit :

> Hi,
>=20
> modify two things.
> 1:
> >> @@ -1316,6 +1324,12 @@ int spi_setup(struct spi_device *spi)
> >>         /* help drivers fail *cleanly* when they need options
> >>          * that aren't supported with their current master
> >>          */
> >> +       if (((spi->mode >> 8) & 0x03) =3D=3D 0x03 ||
> >> +               ((spi->mode >> 10) & 0x03) =3D=3D 0x03) {
> >> +               dev_err(&spi->dev,
> >> +               "setup: can not select dual and quad at the same
> >> time\n")
> >> +               return -EINVAL;
> >> +       }
> >> +               return -EINVAL;
> >> +       }
>=20
> >This code won't work if the constants you added for mode flags change
> >value.  More importantly, anyone searching the code for SPI_TX_DUAL,
> >etc. won't find this code.
>=20
> so use the certain macro to replace.
>=20
> 2:
> >You need to make sure that existing userspace binaries can run
> >unmodified, changing the types will change the layout of the ioctl
> >arguments.  This may mean that you need to add new ioctls if you
> >need to change types.
>=20
> I recovered the SPI_IOC_RD_LSB_FIRST ioctl.
> Add new ioctl to fit u16 mode.
> In addition,may SPI_IOC_RD_LSB_FIRST should be del in a better way.
>=20
> Signed-off-by: wangyuhang <wangyuhang2014@gmail.com>
> ---

>  /* IOCTL commands */
> @@ -54,6 +61,8 @@
>   * @tx_buf: Holds pointer to userspace buffer with transmit data, or
> null.
>   *     If no data is provided, zeroes are shifted out.
>   * @rx_buf: Holds pointer to userspace buffer for receive data, or
> null.
> + * @tx_nbits: number of bits used for writting.
> + * @rx_nbits: number of bits used for reading.
>   * @len: Length of tx and rx buffers, in bytes.
>   * @speed_hz: Temporary override of the device's bitrate.
>   * @bits_per_word: Temporary override of the device's wordsize.
> @@ -85,6 +94,8 @@
>  struct spi_ioc_transfer {
>         __u64           tx_buf;
>         __u64           rx_buf;
> +       __u8            tx_nbits;
> +       __u8            rx_nbits;
>=20
>         __u32           len;
>         __u32           speed_hz;
You still break old userspace ABI.

You need to create a new structure, if you need to add fields.


Matthieu