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-rw-r--r--drivers/spi/spi.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 0276bc3..a525a3a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -607,8 +607,19 @@ EXPORT_SYMBOL_GPL(spi_busnum_to_master);
*/
int spi_setup(struct spi_device *spi)
{
+ unsigned bad_bits;
int status;
+ /* help drivers fail *cleanly* when they need options
+ * that aren't supported with their current master
+ */
+ bad_bits = spi->mode & ~spi->master->mode_bits;
+ if (bad_bits) {
+ dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+ bad_bits);
+ return -EINVAL;
+ }
+
if (!spi->bits_per_word)
spi->bits_per_word = 8;
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