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Date:   Sun, 10 May 2020 10:35:47 +0200
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Boris Brezillon <boris.brezillon@collabora.com>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        <devicetree@vger.kernel.org>, Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Tudor Ambarus <Tudor.Ambarus@microchip.com>,
        <linux-mtd@lists.infradead.org>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Michal Simek <monstr@monstr.eu>,
        Naga Sureshkumar Relli <nagasure@xilinx.com>
Subject: Re: [PATCH v4 7/8] mtd: rawnand: arasan: Add new Arasan NAND
 controller
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Hi Boris,

Boris Brezillon <boris.brezillon@collabora.com> wrote on Sun, 10 May
2020 09:02:30 +0200:

> On Fri,  8 May 2020 19:13:38 +0200
> Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> 
> > +static int anfc_len_to_steps(struct nand_chip *chip, unsigned int len)
> > +{
> > +	unsigned int steps = 1, pktsize = len;
> > +
> > +	while (pktsize > ANFC_MAX_PKT_SIZE) {
> > +		steps *= 2;
> > +		pktsize = DIV_ROUND_UP(len, steps);
> > +	}  
> 
> 
> Same here, you shouldn't have a round_up() but instead complain if
> "len != pkt_size * steps"
> 
> 	if (len % 4)
> 		return -ENOTSUPP;

This is not possible, we need unaligned accesses for NAND detection.

> 
> 	if (len < ANFC_MAX_PKT_SIZE)
> 		return len;
> 
> 	for (steps = 2; steps < ANFC_MAX_STEPS; steps *= 2) {
> 		pkt_size = len / steps;
> 		if (pkt_size <= ANFC_MAX_PKT_SIZE)
> 			break;
> 	}
> 
> 	if (pkt_size * steps != len)
> 		return -ENOTSUPP;
> 
> 	return pkt_size;

The rest looks fine, I will change it and also add these checks in
->exec_op() check_nonly path.