mtd: rawnand: gpio: Move the ECC initialization to ->attach_chip()

The probe function is only supposed to initialize the controller
hardware but not the ECC engine. Indeed, we don't know anything about
the NAND chip(s) at this stage. Let's move the logic initializing the
ECC engine, even pretty simple, to the ->attach_chip() hook which gets
called during nand_scan() routine, after the NAND chip discovery. As
the previously mentioned logic is supposed to parse the DT for us, it
is likely that the chip->ecc.* entries be overwritten. So let's avoid
this by moving these lines to ->attach_chip(), a NAND controller
hook.

Fixes: d7157ff ("mtd: rawnand: Use the ECC framework user input parsing bits")
Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/linux-mtd/20201113123424.32233-2-miquel.raynal@bootlin.com

drivers/mtd/nand/raw/gpio.c

@@ -161,8 +161,17 @@ static int gpio_nand_exec_op(struct nand_chip *chip,
 	return ret;
 }
 
+static int gpio_nand_attach_chip(struct nand_chip *chip)
+{
+	chip->ecc.engine_type = NAND_ECC_ENGINE_TYPE_SOFT;
+	chip->ecc.algo = NAND_ECC_ALGO_HAMMING;
+
+	return 0;
+}
+
 static const struct nand_controller_ops gpio_nand_ops = {
 	.exec_op = gpio_nand_exec_op,
+	.attach_chip = gpio_nand_attach_chip,
 };
 
 #ifdef CONFIG_OF
@@ -342,8 +351,6 @@ static int gpio_nand_probe(struct platform_device *pdev)
 	gpiomtd->base.ops = &gpio_nand_ops;
 
 	nand_set_flash_node(chip, pdev->dev.of_node);
-	chip->ecc.engine_type	= NAND_ECC_ENGINE_TYPE_SOFT;
-	chip->ecc.algo		= NAND_ECC_ALGO_HAMMING;
 	chip->options		= gpiomtd->plat.options;
 	chip->controller	= &gpiomtd->base;