mtd: spinand: Fix MTD_OPS_AUTO_OOB requests

The initial change breaking the logic is
commit 3d1f08b0 ("mtd: spinand: Use the external ECC engine logic")
It inadvertently dropped proper OOB support while doing something
else.

Shortly later, half of it got re-integrated by
commit 868cbe2a ("mtd: spinand: Fix OOB read")
(pointing by the way to a  more early change which had nothing to do
with the issue). Problem is, this commit failed to revert the faulty
change entirely and missed the logic handling MTD_OPS_AUTO_OOB
requests.

Let's fix this mess by re-inserting the missing part now.

Fixes: 868cbe2a ("mtd: spinand: Fix OOB read")
Reported-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210107083813.24283-1-miquel.raynal@bootlin.com

drivers/mtd/nand/spi/core.c

@@ -343,6 +343,7 @@ static int spinand_read_from_cache_op(struct spinand_device *spinand,
 				      const struct nand_page_io_req *req)
 {
 	struct nand_device *nand = spinand_to_nand(spinand);
+	struct mtd_info *mtd = spinand_to_mtd(spinand);
 	struct spi_mem_dirmap_desc *rdesc;
 	unsigned int nbytes = 0;
 	void *buf = NULL;
@@ -382,9 +383,16 @@ static int spinand_read_from_cache_op(struct spinand_device *spinand,
 		memcpy(req->databuf.in, spinand->databuf + req->dataoffs,
 		       req->datalen);
 
-	if (req->ooblen)
-		memcpy(req->oobbuf.in, spinand->oobbuf + req->ooboffs,
-		       req->ooblen);
+	if (req->ooblen) {
+		if (req->mode == MTD_OPS_AUTO_OOB)
+			mtd_ooblayout_get_databytes(mtd, req->oobbuf.in,
+						    spinand->oobbuf,
+						    req->ooboffs,
+						    req->ooblen);
+		else
+			memcpy(req->oobbuf.in, spinand->oobbuf + req->ooboffs,
+			       req->ooblen);
+	}
 
 	return 0;
 }