netdev - Re: [PATCH v3 24/42] mtd: nand: add support for ts72xx

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Message-ID: <ZLqx+Osn3gcHjUph@smile.fi.intel.com>
Date: Fri, 21 Jul 2023 19:27:36 +0300
From: Andy Shevchenko <andy@...nel.org>
To: nikita.shubin@...uefel.me
Cc: Hartley Sweeten <hsweeten@...ionengravers.com>,
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Subject: Re: [PATCH v3 24/42] mtd: nand: add support for ts72xx

On Thu, Jul 20, 2023 at 02:29:24PM +0300, Nikita Shubin via B4 Relay wrote:
> From: Nikita Shubin <nikita.shubin@...uefel.me>
> 
> Technologic Systems has it's own nand controller implementation in CPLD.

...

+ bits.h

> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>

...

> +static int ts72xx_nand_attach_chip(struct nand_chip *chip)
> +{
> +	switch (chip->ecc.engine_type) {
> +	case NAND_ECC_ENGINE_TYPE_SOFT:
> +		if (chip->ecc.algo == NAND_ECC_ALGO_UNKNOWN)
> +			chip->ecc.algo = NAND_ECC_ALGO_HAMMING;
> +		break;
> +	case NAND_ECC_ENGINE_TYPE_ON_HOST:
> +		return -EINVAL;
> +	default:

> +		break;

Here it will return 0, is it a problem?

> +	}
> +
> +	return 0;
> +}

...

> +static int ts72xx_nand_probe(struct platform_device *pdev)
> +{
> +	struct ts72xx_nand_data *data;
> +	struct device_node *child;
> +	struct mtd_info *mtd;
> +	int err;

> +	/* Allocate memory for the device structure (and zero it) */

Useless comment.

> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->controller.ops = &ts72xx_nand_ops;
> +	nand_controller_init(&data->controller);
> +	data->chip.controller = &data->controller;
> +
> +	data->io_base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(data->io_base))
> +		return PTR_ERR(data->io_base);
> +
> +	child = of_get_next_child(pdev->dev.of_node, NULL);

Why not using device property API from day 1?

	fwnode_get_next_child_node()

> +	if (!child)
> +		return dev_err_probe(&pdev->dev, -ENXIO,
> +				"ts72xx controller node should have exactly one child\n");

>From now on you leak the reference count in error path.

> +	nand_set_flash_node(&data->chip, child);
> +	mtd = nand_to_mtd(&data->chip);
> +	mtd->dev.parent = &pdev->dev;
> +
> +	data->chip.legacy.IO_ADDR_R = data->io_base;
> +	data->chip.legacy.IO_ADDR_W = data->io_base;
> +	data->chip.legacy.cmd_ctrl = ts72xx_nand_hwcontrol;
> +	data->chip.legacy.dev_ready = ts72xx_nand_device_ready;
> +
> +	platform_set_drvdata(pdev, data);
> +
> +	/*
> +	 * This driver assumes that the default ECC engine should be TYPE_SOFT.
> +	 * Set ->engine_type before registering the NAND devices in order to
> +	 * provide a driver specific default value.
> +	 */
> +	data->chip.ecc.engine_type = NAND_ECC_ENGINE_TYPE_SOFT;
> +
> +	/* Scan to find existence of the device */
> +	err = nand_scan(&data->chip, 1);
> +	if (err)
> +		return err;
> +
> +	err = mtd_device_parse_register(mtd, NULL, NULL, NULL, 0);
> +	if (err) {
> +		nand_cleanup(&data->chip);

> +		return err;
> +	}
> +
> +	return 0;


These 4 lines can be simply

	return err;

but see above.

> +}

...

> +static void ts72xx_nand_remove(struct platform_device *pdev)
> +{
> +	struct ts72xx_nand_data *data = platform_get_drvdata(pdev);
> +	struct nand_chip *chip = &data->chip;
> +	int ret;
> +
> +	ret = mtd_device_unregister(nand_to_mtd(chip));

> +	WARN_ON(ret);

Why?!  Is it like this in other MTD drivers?

> +	nand_cleanup(chip);
> +}

-- 
With Best Regards,
Andy Shevchenko