• Chris Lesiak's avatar
    spi: Fix zero length xfer bug · 5442dcaa
    Chris Lesiak authored
    This fixes a bug for messages containing both zero length and
    unidirectional xfers.
    
    The function spi_map_msg will allocate dummy tx and/or rx buffers
    for use with unidirectional transfers when the hardware can only do
    a bidirectional transfer.  That dummy buffer will be used in place
    of a NULL buffer even when the xfer length is 0.
    
    Then in the function __spi_map_msg, if he hardware can dma,
    the zero length xfer will have spi_map_buf called on the dummy
    buffer.
    
    Eventually, __sg_alloc_table is called and returns -EINVAL
    because nents == 0.
    
    This fix prevents the error by not using the dummy buffer when
    the xfer length is zero.
    Signed-off-by: default avatarChris Lesiak <chris.lesiak@licor.com>
    Signed-off-by: default avatarMark Brown <broonie@kernel.org>
    5442dcaa
spi.c 99.9 KB