[PATCH] spi: core: use gpio_request_one for configured gpio cs

["Martin Hundebøll" <mnhu-rjjw5hvvQKZaa/9Udqfwiw@public.gmane.org>]

Some gpio controllers requires lines to be configured as outputs to make
subsequent calls to `gpio_set_value()` have any effect.

Add a call to `gpio_request_one()` for configured gpio chip-selects to
make it work on (at least) mvebu gpio controllers.

Signed-off-by: Martin Hundebøll <mnhu-rjjw5hvvQKZaa/9Udqfwiw@public.gmane.org>
---
 drivers/spi/spi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 0725c78b0de6..b7bfc52525aa 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2010,8 +2010,13 @@ static int of_spi_register_master(struct spi_controller *ctlr)
 	for (i = 0; i < ctlr->num_chipselect; i++)
 		cs[i] = -ENOENT;
 
-	for (i = 0; i < nb; i++)
+	for (i = 0; i < nb; i++) {
 		cs[i] = of_get_named_gpio(np, "cs-gpios", i);
+		if (gpio_is_valid(cs[i]) &&
+		    gpio_request_one(cs[i], 0, "spi-cs") < 0)
+			dev_warn(&master->dev,
+				 "gpio_request_one failed for chipselect %i\n", i);
+	}
 
 	return 0;
 }
-- 
2.13.3

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