spi: fix ctrl->num_chipselect constraint

[ Upstream commit f9481b08220d7dc1ff21e296a330ee8b721b44e4 ]

at91sam9g25ek showed the following error at probe:
atmel_spi f0000000.spi: Using dma0chan2 (tx) and dma0chan3 (rx)
for DMA transfers
atmel_spi: probe of f0000000.spi failed with error -22

Commit 0a919ae49223 ("spi: Don't call spi_get_gpio_descs() before device name is set")
moved the calling of spi_get_gpio_descs() after ctrl->dev is set,
but didn't move the !ctrl->num_chipselect check. When there are
chip selects in the device tree, the spi-atmel driver lets the
SPI core discover them when registering the SPI master.
The ctrl->num_chipselect is thus expected to be set by
spi_get_gpio_descs().

Move the !ctlr->num_chipselect after spi_get_gpio_descs() as it was
before the aforementioned commit. While touching this block, get rid
of the explicit comparison with 0 and update the commenting style.

Fixes: 0a919ae49223 ("spi: Don't call spi_get_gpio_descs() before device name is set")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index a83fcddf1dadcf9cc3ad837aaa918c9a2cfa6b53..7f6fb383d7a75d960e0264f3fb86ecf8d3f3b6bb 100644 (file)
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2281,11 +2281,6 @@ int spi_register_controller(struct spi_controller *ctlr)
        if (status)
                return status;
 
-       /* even if it's just one always-selected device, there must
-        * be at least one chipselect
-        */
-       if (ctlr->num_chipselect == 0)
-               return -EINVAL;
        if (ctlr->bus_num >= 0) {
                /* devices with a fixed bus num must check-in with the num */
                mutex_lock(&board_lock);
@@ -2356,6 +2351,13 @@ int spi_register_controller(struct spi_controller *ctlr)
                }
        }
 
+       /*
+        * Even if it's just one always-selected device, there must
+        * be at least one chipselect.
+        */
+       if (!ctlr->num_chipselect)
+               return -EINVAL;
+
        status = device_add(&ctlr->dev);
        if (status < 0) {
                /* free bus id */