Hi Andrew Ruder,

On Wed, Oct 23, 2013 at 5:41 AM, Andrew Ruder andrew.ruder@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.ruder@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!