Re: [RFC PATCH 25/27] mtd: nand: Add helpers to manage ECC engines and configurationsND

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Brian Norris <computersforpeace@gmail.com>,
	Vignesh R <vigneshr@ti.com>,
	Tudor Ambarus <Tudor.Ambarus@microchip.com>,
	Julien Su <juliensu@mxic.com.tw>,
	Richard Weinberger <richard@nod.at>,
	Schrempf Frieder <frieder.schrempf@kontron.de>,
	Marek Vasut <marek.vasut@gmail.com>,
	linux-mtd@lists.infradead.org,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Mason Yang <masonccyang@mxic.com.tw>,
	David Woodhouse <dwmw2@infradead.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH 25/27] mtd: nand: Add helpers to manage ECC engines and configurationsND
Date: Tue, 26 Feb 2019 16:59:23 +0100	[thread overview]
Message-ID: <20190226165923.535f63f7@xps13> (raw)
In-Reply-To: <20190225194803.58fb8efc@collabora.com>

Hi Boris,

Boris Brezillon <boris.brezillon@collabora.com> wrote on Mon, 25 Feb
2019 19:48:03 +0100:

> > > Also, the parsing of the DT (in nand_ecc_read_user_conf()) gives me the
> > > user ECC mode and algo, so I cannot let the raw NAND core (or a raw
> > > NAND controller driver) or the SPI NAND core decide which mode is the
> > > default if not provided by the user.    
> > 
> > Except this prop is optional in most cases, and the default value is
> > not always the same, which is why I think this ECC engine retrieval step
> > should be left to each sub-layer (and sometimes to the controller driver
> > behind it). Maybe you can provide helpers to help with that, but I
> > don't think taking this decision here, based on the bus type, is a good
> > idea. And I also don't like the idea of adding a new SPINAND type.  
> 
> Hm, after thinking a bit more about it, maybe we could have something
> in-between: let the controller driver or sub-layer specify what the
> default values are (provider/mode and possibly algorithm if that makes
> sense) so that this generic function can use these defaults when
> nand->ecc.user_conf.{mode,algo} == UNKNOWN.

Having a "default_provider" in struct nand_ecc could to the trick. It
would be filled by the controller drivers/sublayers before
nanddev_ecc_engine_init() is called.

Thanks,
Miquèl

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