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-rw-r--r--drivers/spi/spidev.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 38b60ad0eda0..630f781aeb19 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -55,9 +55,16 @@
static unsigned long minors[N_SPI_MINORS / BITS_PER_LONG];
-/* Bit masks for spi_device.mode management */
-#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL)
-
+/* Bit masks for spi_device.mode management. Note that incorrect
+ * settings for CS_HIGH and 3WIRE can cause *lots* of trouble for other
+ * devices on a shared bus: CS_HIGH, because this device will be
+ * active when it shouldn't be; 3WIRE, because when active it won't
+ * behave as it should.
+ *
+ * REVISIT should changing those two modes be privileged?
+ */
+#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
+ | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP)
struct spidev_data {
struct device dev;