Some SPI connected devices do not have any CS line connected as
some devices are alway enabled. Indeed, until now, a common
workaround was to assign to num_chipselect a -1 value or 255
(num_chipselect is unsigned).
In this case do not fail and defer to the SPI device drivers the
responsibility to check whether the num-cs is '0'.
Signed-off-by: Andi Shyti <andi.sh...@samsung.com>
---
drivers/spi/spi.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 77e6e45..f22dc27 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -504,8 +504,13 @@ int spi_add_device(struct spi_device *spi)
struct device *dev = master->dev.parent;
int status;
- /* Chipselects are numbered 0..max; validate. */
- if (spi->chip_select >= master->num_chipselect) {
+ /*
+ * Chipselects are numbered 0..max; validate.
+ * If there is no chip select (i.e. num_chipselect == 0),
+ * the comparison doesn't make sense.
+ */
+ if (master->num_chipselect &&
+ spi->chip_select >= master->num_chipselect) {
dev_err(dev, "cs%d >= max %d\n",
spi->chip_select,
master->num_chipselect);
@@ -1851,12 +1856,6 @@ int spi_register_master(struct spi_master *master)
if (status)
return status;
- /* even if it's just one always-selected device, there must
- * be at least one chipselect
- */
- if (master->num_chipselect == 0)
- return -EINVAL;
-
if ((master->bus_num < 0) && master->dev.of_node)
master->bus_num = of_alias_get_id(master->dev.of_node, "spi");
--
2.8.1
