linux-kernel - [PATCH v2 3/3] mtd: rawnand: sunxi: Precompute the ECC

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Message-Id: <20230204143520.9682-4-samuel@sholland.org>
Date:   Sat,  4 Feb 2023 08:35:20 -0600
From:   Samuel Holland <samuel@...lland.org>
To:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>
Cc:     Boris Brezillon <bbrezillon@...nel.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Samuel Holland <samuel@...lland.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-sunxi@...ts.linux.dev
Subject: [PATCH v2 3/3] mtd: rawnand: sunxi: Precompute the ECC_CTL register value

The value computed by this function never changes for a given chip.
Compute the whole register value once up front, instead of every time
the ECC engine is enabled.

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

Changes in v2:
 - Split ECC_CTL precomputation and structure updates to two patches

 drivers/mtd/nand/raw/sunxi_nand.c | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index a0d0cb17c150..13e3e0198d15 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -172,10 +172,10 @@ struct sunxi_nand_chip_sel {
 /**
  * struct sunxi_nand_hw_ecc - stores information related to HW ECC support
  *
- * @mode: the sunxi ECC mode field deduced from ECC requirements
+ * @ecc_ctl: ECC_CTL register value for this NAND chip
  */
 struct sunxi_nand_hw_ecc {
-	int mode;
+	u32 ecc_ctl;
 };
 
 /**
@@ -689,26 +689,15 @@ static void sunxi_nfc_hw_ecc_enable(struct nand_chip *nand)
 {
 	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
-	u32 ecc_ctl;
-
-	ecc_ctl = readl(nfc->regs + NFC_REG_ECC_CTL);
-	ecc_ctl &= ~(NFC_ECC_MODE_MSK | NFC_ECC_PIPELINE |
-		     NFC_ECC_BLOCK_SIZE_MSK);
-	ecc_ctl |= NFC_ECC_EN | NFC_ECC_MODE(sunxi_nand->ecc.mode) |
-		   NFC_ECC_EXCEPTION | NFC_ECC_PIPELINE;
-
-	if (nand->ecc.size == 512)
-		ecc_ctl |= NFC_ECC_BLOCK_512;
 
-	writel(ecc_ctl, nfc->regs + NFC_REG_ECC_CTL);
+	writel(sunxi_nand->ecc.ecc_ctl, nfc->regs + NFC_REG_ECC_CTL);
 }
 
 static void sunxi_nfc_hw_ecc_disable(struct nand_chip *nand)
 {
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
 
-	writel(readl(nfc->regs + NFC_REG_ECC_CTL) & ~NFC_ECC_EN,
-	       nfc->regs + NFC_REG_ECC_CTL);
+	writel(0, nfc->regs + NFC_REG_ECC_CTL);
 }
 
 static inline void sunxi_nfc_user_data_to_buf(u32 user_data, u8 *buf)
@@ -1693,8 +1682,6 @@ static int sunxi_nand_hw_ecc_ctrl_init(struct nand_chip *nand,
 		return -ENOTSUPP;
 	}
 
-	sunxi_nand->ecc.mode = i;
-
 	/* HW ECC always request ECC bytes for 1024 bytes blocks */
 	ecc->bytes = DIV_ROUND_UP(ecc->strength * fls(8 * 1024), 8);
 
@@ -1726,6 +1713,12 @@ static int sunxi_nand_hw_ecc_ctrl_init(struct nand_chip *nand,
 	ecc->read_oob_raw = nand_read_oob_std;
 	ecc->write_oob_raw = nand_write_oob_std;
 
+	sunxi_nand->ecc.ecc_ctl = NFC_ECC_MODE(i) | NFC_ECC_EXCEPTION |
+				  NFC_ECC_PIPELINE | NFC_ECC_EN;
+
+	if (ecc->size == 512)
+		sunxi_nand->ecc.ecc_ctl |= NFC_ECC_BLOCK_512;
+
 	return 0;
 }
 
-- 
2.37.4