in fusion/mptspi.c [991:1012]
static void mptspi_write_dt(struct scsi_target *starget, int dt)
{
struct _CONFIG_PAGE_SCSI_DEVICE_1 pg1;
u32 nego;
if (spi_period(starget) == -1)
mptspi_read_parameters(starget);
if (!dt && spi_period(starget) < 10)
spi_period(starget) = 10;
spi_dt(starget) = dt;
nego = mptspi_getRP(starget);
pg1.RequestedParameters = cpu_to_le32(nego);
pg1.Reserved = 0;
pg1.Configuration = 0;
mptspi_write_spi_device_pg1(starget, &pg1);
}