[PATCH v2] staging: mt7621-spi: drop support for SPI mode 1/2/3

[Chuanhong Guo]

Chuanhong Guo <gch981213 at gmail.com> 于2018年12月6日周四 下午7:19写道：
>
> As explained in previous patch, this SPI controller seems to be
> tested on SPI flash only before mass production and some bits are
> swizzled under other SPI modes probably due to incorrect wiring
> inside the silicon. Drop implementation of SPI mode 1/2/3 since
> they are broken.
>
> Also drop RT2880_SPI_MODE_BITS macro because we now have only
> SPI_LSB_FIRST implemented and the mode_bits is so short that we
> don't need a macro there.
>
> Signed-off-by: Chuanhong Guo <gch981213 at gmail.com>
> ---
> Changes since v1:
>  drop unspoorted modes from mode_bits instead of reject them
>   in mt7621_spi_prepare.
>  dropped RT2880_SPI_MODES_BITS macro
>  modified code comment
>
>  drivers/staging/mt7621-spi/spi-mt7621.c | 25 ++++++++-----------------
>  1 file changed, 8 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/staging/mt7621-spi/spi-mt7621.c b/drivers/staging/mt7621-spi/spi-mt7621.c
> index f115a8bf652d..ba2d24ce0eb1 100644
> --- a/drivers/staging/mt7621-spi/spi-mt7621.c
> +++ b/drivers/staging/mt7621-spi/spi-mt7621.c
> @@ -55,9 +55,6 @@
>  #define MT7621_CPOL            BIT(4)
>  #define MT7621_LSB_FIRST       BIT(3)
>
> -#define RT2880_SPI_MODE_BITS   (SPI_CPOL | SPI_CPHA |          \
> -                                SPI_LSB_FIRST | SPI_CS_HIGH)
> -
>  struct mt7621_spi;
>
>  struct mt7621_spi {
> @@ -136,20 +133,14 @@ static int mt7621_spi_prepare(struct spi_device *spi, unsigned int speed)
>         if (spi->mode & SPI_LSB_FIRST)
>                 reg |= MT7621_LSB_FIRST;
>
> +
Sorry. I accidentally added a line here and it's complained by
checkpatch.pl. I'll send a v3 later.
> +       /* This SPI controller seems to be tested on SPI flash only
> +        * and some bits are swizzled under other SPI modes probably
> +        * due to incorrect wiring inside the silicon. Only mode 0
> +        * works correctly.
> +        */
>         reg &= ~(MT7621_CPHA | MT7621_CPOL);
> -       switch (spi->mode & (SPI_CPOL | SPI_CPHA)) {
> -       case SPI_MODE_0:
> -               break;
> -       case SPI_MODE_1:
> -               reg |= MT7621_CPHA;
> -               break;
> -       case SPI_MODE_2:
> -               reg |= MT7621_CPOL;
> -               break;
> -       case SPI_MODE_3:
> -               reg |= MT7621_CPOL | MT7621_CPHA;
> -               break;
> -       }
> +
>         mt7621_spi_write(rs, MT7621_SPI_MASTER, reg);
>
>         return 0;
> @@ -367,7 +358,7 @@ static int mt7621_spi_probe(struct platform_device *pdev)
>                 return -ENOMEM;
>         }
>
> -       master->mode_bits = RT2880_SPI_MODE_BITS;
> +       master->mode_bits = SPI_LSB_FIRST;
>
>         master->setup = mt7621_spi_setup;
>         master->transfer_one_message = mt7621_spi_transfer_one_message;
> --
> 2.19.1
>