Re: [PATCH] [SPI] SPI100k: Fix 8-bit and RX-only transfers

[Cory Maccarrone <darkstar6262@gmail.com>]

On Sat, May 29, 2010 at 5:12 PM, Cory Maccarrone <darkstar6262@gmail.com> wrote:
> This change fixes 8-bit transfers and RX-only transfers.  The
> SPI100k framework requires minimum 16-bit words to be written, so 8-bit
> transfers must be shited by 8 bits and sent out as a 16-bit word.
>
> Additionally, receive-only transfers were failing due to the
> perceived need to fill the TX buffer with something.  This is in
> fact not needed.
>
> Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
> ---
>  drivers/spi/omap_spi_100k.c |   23 ++++++++++++-----------
>  1 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/spi/omap_spi_100k.c b/drivers/spi/omap_spi_100k.c
> index 24668b3..9bd1c92 100644
> --- a/drivers/spi/omap_spi_100k.c
> +++ b/drivers/spi/omap_spi_100k.c
> @@ -141,7 +141,12 @@ static void spi100k_write_data(struct spi_master *master, int len, int data)
>  {
>        struct omap1_spi100k *spi100k = spi_master_get_devdata(master);
>
> -       /* write 16-bit word */
> +       /* write 16-bit word, shifting 8-bit data if necessary */
> +       if (len <= 8) {
> +               data <<= 8;
> +               len = 16;
> +       }
> +
>        spi100k_enable_clock(master);
>        writew( data , spi100k->base + SPI_TX_MSB);
>
> @@ -162,6 +167,10 @@ static int spi100k_read_data(struct spi_master *master, int len)
>        int dataH,dataL;
>        struct omap1_spi100k *spi100k = spi_master_get_devdata(master);
>
> +       /* Always do at least 16 bits */
> +       if (len <= 8)
> +               len = 16;
> +
>        spi100k_enable_clock(master);
>        writew(SPI_CTRL_SEN(0) |
>               SPI_CTRL_WORD_SIZE(len) |
> @@ -214,10 +223,6 @@ omap1_spi100k_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
>        c = count;
>        word_len = cs->word_len;
>
> -       /* RX_ONLY mode needs dummy data in TX reg */
> -       if (xfer->tx_buf == NULL)
> -               spi100k_write_data(spi->master,word_len, 0);
> -
>        if (word_len <= 8) {
>                u8              *rx;
>                const u8        *tx;
> @@ -227,9 +232,9 @@ omap1_spi100k_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
>                do {
>                        c-=1;
>                        if (xfer->tx_buf != NULL)
> -                               spi100k_write_data(spi->master,word_len, *tx);
> +                               spi100k_write_data(spi->master, word_len, *tx++);
>                        if (xfer->rx_buf != NULL)
> -                               *rx = spi100k_read_data(spi->master,word_len);
> +                               *rx++ = spi100k_read_data(spi->master, word_len);
>                } while(c);
>        } else if (word_len <= 16) {
>                u16             *rx;
> @@ -380,10 +385,6 @@ static void omap1_spi100k_work(struct work_struct *work)
>                        if (t->len) {
>                                unsigned count;
>
> -                               /* RX_ONLY mode needs dummy data in TX reg */
> -                               if (t->tx_buf == NULL)
> -                                       spi100k_write_data(spi->master, 8, 0);
> -
>                                count = omap1_spi100k_txrx_pio(spi, t);
>                                m->actual_length += count;
>
> --
> 1.7.0.4
>
>

Adding another name to the list.

- Cory