linux-kernel - Re: [LINUX PATCH v9 4/4] mtd: rawnand: pl353: Add basic driver for arm pl353 smc nand interface

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Date:   Fri, 8 Jun 2018 14:35:49 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Naga Sureshkumar Relli <nagasure@...inx.com>
Cc:     "boris.brezillon@...tlin.com" <boris.brezillon@...tlin.com>,
        "richard@....at" <richard@....at>,
        "wmw2@...radead.org" <wmw2@...radead.org>,
        "computersforpeace@...il.com" <computersforpeace@...il.com>,
        "marek.vasut@...il.com" <marek.vasut@...il.com>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "mmayer@...adcom.com" <mmayer@...adcom.com>,
        "rogerq@...com" <rogerq@...com>,
        "ladis@...ux-mips.org" <ladis@...ux-mips.org>,
        "ada@...rsis.com" <ada@...rsis.com>,
        "honghui.zhang@...iatek.com" <honghui.zhang@...iatek.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "nagasureshkumarrelli@...il.com" <nagasureshkumarrelli@...il.com>
Subject: Re: [LINUX PATCH v9 4/4] mtd: rawnand: pl353: Add basic driver for
 arm pl353 smc nand interface

Hi Naga,

> > > +		ecc->read_page = pl353_nand_read_page_hwecc;
> > > +		ecc->size = PL353_NAND_ECC_SIZE;
> > > +		ecc->write_page = pl353_nand_write_page_hwecc;
> > > +		pl353_smc_set_ecc_pg_size(mtd->writesize);
> > > +		switch (mtd->writesize) {
> > > +		case SZ_512:
> > > +		case SZ_1K:
> > > +		case SZ_2K:
> > > +			pl353_smc_set_ecc_mode(PL353_SMC_ECCMODE_APB);
> > > +			break;
> > > +		default:
> > > +			/*
> > > +			 * The software ECC routines won't work with the
> > > +			 * SMC controller
> > > +			 */
> > > +			ecc->calculate = nand_calculate_ecc;
> > > +			ecc->correct = nand_correct_data;
> > > +			ecc->size = 256;
> > > +			break;
> > > +		}
> > > +		if (mtd->writesize <= SZ_512)
> > > +			xnand->addr_cycles = 1;
> > > +		else
> > > +			xnand->addr_cycles = 2;
> > > +
> > > +		if (chip->options & NAND_ROW_ADDR_3)
> > > +			xnand->addr_cycles += 3;
> > > +		else
> > > +			xnand->addr_cycles += 2;
> > > +
> > > +		if (mtd->oobsize == 16)
> > > +			mtd_set_ooblayout(mtd, &pl353_ecc_ooblayout16_ops);
> > > +		else if (mtd->oobsize == 64)
> > > +			mtd_set_ooblayout(mtd, &pl353_ecc_ooblayout64_ops);  
> > 
> > else?  
> You mean to say, add an error condition?

I do.

> >   
> > > +	}
> > > +}
> > > +
> > > +/**
> > > + * pl353_nand_probe - Probe method for the NAND driver
> > > + * @pdev:	Pointer to the platform_device structure
> > > + *
> > > + * This function initializes the driver data structures and the hardware.
> > > + *
> > > + * Return:	0 on success or error value on failure
> > > + */
> > > +static int pl353_nand_probe(struct platform_device *pdev) {
> > > +	struct pl353_nand_info *xnand;  
> > 
> > xnand is a strange name, more and more because its a bout NAND controller data, not NAND
> > chip.  
> We added this name to represent Xilinx Nand(xnand), 
> >   

I see where the x comes from.

Maybe just nfc (for NAND flash controller) or xnfc if you prefer. What
I want is to clearly make the distinction between what is a NAND chip,
what is a NAND controller.

> > > +	struct mtd_info *mtd;
> > > +	struct nand_chip *nand_chip;  
> > 
> > This one you can call it just "nand" or "chip".  
> Ok, I will update.
> 
> >   
> > > +	struct resource *res;
> > > +
> > > +	xnand = devm_kzalloc(&pdev->dev, sizeof(*xnand), GFP_KERNEL);
> > > +	if (!xnand)
> > > +		return -ENOMEM;
> > > +
> > > +	/* Map physical address of NAND flash */
> > > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > +	xnand->nand_base = devm_ioremap_resource(&pdev->dev, res);
> > > +	if (IS_ERR(xnand->nand_base))
> > > +		return PTR_ERR(xnand->nand_base);
> > > +
> > > +	nand_chip = &xnand->chip;
> > > +	mtd = nand_to_mtd(nand_chip);
> > > +	nand_chip->exec_op = pl353_nfc_exec_op;
> > > +	nand_set_controller_data(nand_chip, xnand);
> > > +	mtd->priv = nand_chip;
> > > +	mtd->owner = THIS_MODULE;
> > > +	mtd->name = PL353_NAND_DRIVER_NAME;  
> > 
> > A label property in the DT might overwrite this value.  
> Could you please explain a bit more ?
> 

I meant something like this:

https://elixir.bootlin.com/linux/latest/source/drivers/mtd/nand/raw/marvell_nand.c#L2515

Thanks,
Miquèl