[PATCH v2 1/1] mtd: nand: raw: atmel: Add error handling when rb-gpios missing

[Alexander Dahl]

Adapt behaviour to Linux kernel driver.

The return value of gpio_request_by_name_nodev() was not checked before,
and thus in case 'rb-gpios' was missing in DT, rb.type was set to
ATMEL_NAND_GPIO_RB nevertheless, leading to output like this for
example (on sam9x60-curiosity with the line removed from dts):

    NAND:  Could not find valid ONFI parameter page; aborting
    device found, Manufacturer ID: 0xc2, Chip ID: 0xdc
    Macronix NAND 512MiB 3,3V 8-bit
    512 MiB, SLC, erase size: 256 KiB, page size: 4096, OOB size: 64
    atmel-nand-controller nand-controller: NAND scan failed: -22
    Failed to probe nand driver (err = -22)
    Failed to initialize NAND controller. (error -22)
    0 MiB

Note: not having that gpio assigned in dts is possible, the driver does
not override nand_chip->dev_ready() then and a generic solution is used.

Fixes: 6a8dfd57220d ("nand: atmel: Add DM based NAND driver")
Signed-off-by: Alexander Dahl <ada at thorsis.com>
---

Notes:
    v1 -> v2:
    
    - Only issue error message if error is not ENOENT.  If the node just is
      missing, move on without error message.

 drivers/mtd/nand/raw/atmel/nand-controller.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c b/drivers/mtd/nand/raw/atmel/nand-controller.c
index 2b29c8def6..fa962ba591 100644
--- a/drivers/mtd/nand/raw/atmel/nand-controller.c
+++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
@@ -1600,10 +1600,13 @@ static struct atmel_nand *atmel_nand_create(struct atmel_nand_controller *nc,
 			nand->cs[i].rb.type = ATMEL_NAND_NATIVE_RB;
 			nand->cs[i].rb.id = val;
 		} else {
-			gpio_request_by_name_nodev(np, "rb-gpios", 0,
-						   &nand->cs[i].rb.gpio,
-						   GPIOD_IS_IN);
-			nand->cs[i].rb.type = ATMEL_NAND_GPIO_RB;
+			ret = gpio_request_by_name_nodev(np, "rb-gpios", 0,
+							 &nand->cs[i].rb.gpio,
+							 GPIOD_IS_IN);
+			if (ret && ret != -ENOENT)
+				dev_err(nc->dev, "Failed to get R/B gpio (err = %d)\n", ret);
+			if (!ret)
+				nand->cs[i].rb.type = ATMEL_NAND_GPIO_RB;
 		}
 
 		gpio_request_by_name_nodev(np, "cs-gpios", 0,
-- 
2.30.2