linux-kernel - [PATCH 6/7] mtd: rawnand: sunxi: Update OOB layout to match hardware

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Message-Id: <20221229181526.53766-7-samuel@sholland.org>
Date:   Thu, 29 Dec 2022 12:15:25 -0600
From:   Samuel Holland <samuel@...lland.org>
To:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>
Cc:     Boris Brezillon <bbrezillon@...nel.org>,
        Samuel Holland <samuel@...lland.org>,
        Brian Norris <computersforpeace@...il.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-sunxi@...ts.linux.dev
Subject: [PATCH 6/7] mtd: rawnand: sunxi: Update OOB layout to match hardware

When using the hardware ECC engine, the OOB data is made available in
the NFC_REG_USER_DATA registers, one 32-bit word per ECC step. Any
additional bytes are only accessible through raw reads and software
descrambling. For efficiency, and to match the vendor driver, ignore
these extra bytes.

Signed-off-by: Samuel Holland <samuel@...lland.org>
---

 drivers/mtd/nand/raw/sunxi_nand.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index 8e873f4fec9a..a3bc9f7f9e5a 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -1604,6 +1604,13 @@ static int sunxi_nand_ooblayout_free(struct mtd_info *mtd, int section,
 		return 0;
 	}
 
+	/*
+	 * The controller does not provide access to OOB bytes
+	 * past the end of the ECC data.
+	 */
+	if (section == ecc->steps && ecc->engine_type == NAND_ECC_ENGINE_TYPE_ON_HOST)
+		return -ERANGE;
+
 	oobregion->offset = section * (ecc->bytes + 4);
 
 	if (section < ecc->steps)
-- 
2.37.4