diff options
Diffstat (limited to 'drivers/mmc')
| -rw-r--r-- | drivers/mmc/host/mmc_spi.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c index 240608cc7ae..a461017ce5c 100644 --- a/drivers/mmc/host/mmc_spi.c +++ b/drivers/mmc/host/mmc_spi.c @@ -1313,6 +1313,12 @@ static int mmc_spi_probe(struct spi_device *spi) struct mmc_spi_host *host; int status; + /* We rely on full duplex transfers, mostly to reduce + * per-transfer overheads (by making fewer transfers). + */ + if (spi->master->flags & SPI_MASTER_HALF_DUPLEX) + return -EINVAL; + /* MMC and SD specs only seem to care that sampling is on the * rising edge ... meaning SPI modes 0 or 3. So either SPI mode * should be legit. We'll use mode 0 since the steady state is 0, |