linux-kernel - Re: [LINUX PATCH v14] mtd: rawnand: pl353: Add basic driver for arm pl353 smc nand interface

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Date:   Tue, 23 Apr 2019 14:45:27 +0200
From:   Helmut Grohne <helmut.grohne@...enta.de>
To:     Naga Sureshkumar Relli <naga.sureshkumar.relli@...inx.com>
CC:     <bbrezillon@...nel.org>, <miquel.raynal@...tlin.com>,
        <richard@....at>, <dwmw2@...radead.org>,
        <computersforpeace@...il.com>, <marek.vasut@...il.com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <michals@...inx.com>, <nagasureshkumarrelli@...il.com>
Subject: Re: [LINUX PATCH v14] mtd: rawnand: pl353: Add basic driver for arm
 pl353 smc nand interface

WARNING: This driver might brick the hardware. See below.

Hi Naga,

On Mon, Apr 15, 2019 at 04:40:13PM +0530, Naga Sureshkumar Relli wrote:
> Changes in v14:
>  - Removed legacy hooks as per Miquel comments

Thank you for the update.

> +static inline int pl353_wait_for_dev_ready(struct nand_chip *chip)
> +{
> +	unsigned long timeout = jiffies + PL353_NAND_DEV_BUSY_TIMEOUT;
> +
> +	do {
> +		if (pl353_smc_get_nand_int_status_raw()) {
> +			pl353_smc_clr_nand_int();
> +			break;

A closing brace is missing here. This causes a compilation failure.

> +
> +		cpu_relax();

You previously used cond_resched (via nand_wait_ready) here. Why did you
change it to cpu_relax()?

> +	} while (!time_after_eq(jiffies, timeout));
> +
> +	if (time_after_eq(jiffies, timeout)) {
> +		pr_err("%s timed out\n", __func__);
> +		return -ETIMEDOUT;
> +	}
> +
> +	return 0;
> +}


> +static int pl353_nand_read_page_hwecc(struct nand_chip *chip,
> +				      u8 *buf, int oob_required, int page)
> +{
> +	int i, stat, eccsize = chip->ecc.size;
> +	int eccbytes = chip->ecc.bytes;
> +	int eccsteps = chip->ecc.steps;
> +	u8 *p = buf;
> +	u8 *ecc_calc = chip->ecc.calc_buf;
> +	u8 *ecc = chip->ecc.code_buf;
> +	unsigned int max_bitflips = 0;
> +	u8 *oob_ptr;
> +	u32 ret;
> +	unsigned long data_phase_addr;
> +	unsigned long nand_offset = (unsigned long __force)xnfc->regs;

The variable xnfc is undeclared here. Consider swapping the line with
the next one.

> +	struct pl353_nand_controller *xnfc = to_pl353_nand(chip);
> +	struct mtd_info *mtd = nand_to_mtd(chip);

After loading the driver, the device does not work. The dmesg output is:

nand: device found, Manufacturer ID: 0x2c, Chip ID: 0xda
nand: Micron MT29F2G08ABAEAWP
nand: 256 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 64
Bad block table not found for chip 0
Bad block table not found for chip 0
Scanning device for bad blocks
nand_bbt: error while writing BBT block -524
nand_bbt: error while writing BBT block -524
nand_bbt: error while writing BBT block -524
nand_bbt: error while writing BBT block -524
No space left to write bad block table
nand_bbt: error while writing bad block table -28
pl353-nand e1000000.flash: could not scan the nand chip
pl353-nand: probe of e1000000.flash failed with error -28

After trying the driver, the flash chip was bricked. Neither the old
driver nor the uboot-xlnx driver nor the Xilinx fsbl are able to talk to
the chip afterwards. This behaviour persists even after a full power
cycle. I'll try reinitializing the flash chip next. I've only seen this
behaviour once, so there is a slight chance that the cause is something
else.

Helmut