Hi Andrew Ruder,
On Wed, Oct 23, 2013 at 5:41 AM, Andrew Ruder
<andrew.ru...@elecsyscorp.com> wrote:
> This mirrors the conventions used in other SPI drivers (kirkwood,
> davinci, atmel, et al) where the din/dout buffer can be NULL when the
> received/transmitted data isn't important. This reduces the need for
> allocating additional buffers when write-only/read-only functionality is
> needed.
>
> In the din == NULL case, the received data is simply not stored. In the
> dout == NULL case, zeroes are transmitted.
>
> Signed-off-by: Andrew Ruder <andrew.ru...@elecsyscorp.com>
> ---
> drivers/spi/soft_spi.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/spi/soft_spi.c b/drivers/spi/soft_spi.c
> index 5d22351..5fdd091 100644
> --- a/drivers/spi/soft_spi.c
> +++ b/drivers/spi/soft_spi.c
> @@ -137,9 +137,15 @@ int spi_xfer(struct spi_slave *slave, unsigned int
> bitlen,
> * Check if it is time to work on a new byte.
> */
> if((j % 8) == 0) {
> - tmpdout = *txd++;
> + if (txd) {
> + tmpdout = *txd++;
> + } else {
> + tmpdout = 0;
> + }
> if(j != 0) {
> - *rxd++ = tmpdin;
> + if (rxd) {
> + *rxd++ = tmpdin;
> + }
> }
> tmpdin = 0;
> }
> @@ -164,9 +170,11 @@ int spi_xfer(struct spi_slave *slave, unsigned int
> bitlen,
> * bits over to left-justify them. Then store the last byte
> * read in.
> */
> - if((bitlen % 8) != 0)
> - tmpdin <<= 8 - (bitlen % 8);
> - *rxd++ = tmpdin;
> + if (rxd) {
> + if((bitlen % 8) != 0)
> + tmpdin <<= 8 - (bitlen % 8);
> + *rxd++ = tmpdin;
> + }
>
> if (flags & SPI_XFER_END)
> spi_cs_deactivate(slave);
> --
I'm not sure does this NULL buf config stuff will works all boards as
you listed.
I guess ie the reason the earlier code doesn't have this.
Does this tested on your board? any possibility to test others too.
Jean-Christophe, any comments here!
--
Thanks,
Jagan.
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