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Date: Thu, 16 Oct 2014 14:39:47 +0100
From: Mark Rutland <mark.rutland@arm.com>
To: Josh Wu <josh.wu@atmel.com>
Subject: Re: [PATCH v3] mtd: atmel_nand: make PMECC lookup table and offset
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[...]

> >> That said, if we can build this dynamically, can't we always do so, and
> >> never need this property?
> >
> > Since board like at91sam9x5, sama5d3xek has a rom lookup table. And 
> > the sama5d4ek has no rom lookup table.
> > To present this, I make this property as optional.
> >
> > But yes, the pmecc lookup table related properties can be removed as 
> > driver can build it in runtime.
> > The cost is we need to use more memory to store the table.
> 
> In precisely, the table need to 32k bytes memory for 512-sector, and 64k 
> bytes for 1024-sector.
> 
> Also I spend time to testing the performance of this version.
> Compare with the version which use the SRAM rom lookup table, this 
> version (build table in runtim) cost about 5~10ms more.
> 
> So I prefer to keep this property as optional.

Sure. It sounds like it's always possible to ignore it later if we
choose to.

I just wouldn't mention what the driver should do in the binding --
whether or not the property is optional, the behaviour of the driver is
not a detail of the device.

Thanks,
Mark.