linux-kernel - [PATCH 3.16 014/134] mtd: nand: fsmc: fix NAND width handling

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Date:   Fri, 18 Aug 2017 14:13:20 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Linus Walleij" <linus.walleij@...aro.org>,
        "Boris Brezillon" <boris.brezillon@...e-electrons.com>,
        "Thomas Petazzoni" <thomas.petazzoni@...e-electrons.com>
Subject: [PATCH 3.16 014/134] mtd: nand: fsmc: fix NAND width handling

3.16.47-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>

commit ee56874f23e5c11576540bd695177a5ebc4f4352 upstream.

In commit eea628199d5b ("mtd: Add device-tree support to fsmc_nand"),
Device Tree support was added to the fmsc_nand driver. However, this
code has a bug in how it handles the bank-width DT property to set the
bus width.

Indeed, in the function fsmc_nand_probe_config_dt() that parses the
Device Tree, it sets pdata->width to either 8 or 16 depending on the
value of the bank-width DT property.

Then, the ->probe() function will test if pdata->width is equal to
FSMC_NAND_BW16 (which is 2) to set NAND_BUSWIDTH_16 in
nand->options. Therefore, with the DT probing, this condition will never
match.

This commit fixes that by removing the "width" field from
fsmc_nand_platform_data and instead have the fsmc_nand_probe_config_dt()
function directly set the appropriate nand->options value.

It is worth mentioning that if this commit gets backported to older
kernels, prior to the drop of non-DT probing, then non-DT probing will
be broken because nand->options will no longer be set to
NAND_BUSWIDTH_16.

Fixes: eea628199d5b ("mtd: Add device-tree support to fsmc_nand")
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
[bwh: Backported to 3.16: keep fsmc_and_platform_data::width and the
 test in fsmc_nand_probe()]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/mtd/nand/fsmc_nand.c
+++ b/drivers/mtd/nand/fsmc_nand.c
@@ -874,18 +874,19 @@ static int fsmc_nand_probe_config_dt(str
 	struct fsmc_nand_platform_data *pdata = dev_get_platdata(&pdev->dev);
 	u32 val;

-	/* Set default NAND width to 8 bits */
-	pdata->width = 8;
+	pdata->options = 0;
+
 	if (!of_property_read_u32(np, "bank-width", &val)) {
 		if (val == 2) {
-			pdata->width = 16;
+			pdata->options |= NAND_BUSWIDTH_16;
 		} else if (val != 1) {
 			dev_err(&pdev->dev, "invalid bank-width %u\n", val);
 			return -EINVAL;
 		}
 	}
+
 	if (of_get_property(np, "nand-skip-bbtscan", NULL))
-		pdata->options = NAND_SKIP_BBTSCAN;
+		pdata->options |= NAND_SKIP_BBTSCAN;

 	pdata->nand_timings = devm_kzalloc(&pdev->dev,
 				sizeof(*pdata->nand_timings), GFP_KERNEL);