Re: [RFC PATCH 03/27] mtd: nand: Introduce the ECC engine abstraction

[Miquel Raynal <miquel.raynal@bootlin.com>]

> > > > Furthermore if this is just a hook to do reference counting.      
> > > 
> > > Well, what this put() does depends on the class of engine. For SW and
> > > on-die ECC it can be a NOOP (that's true only if you keep the approach
> > > where you have a single instance shared by everyone for SW-based ECC
> > > engines).
> > > For HW-controller-side ECC engines, you'll have to call device_get() on
> > > the parent device in your nand_get_hw_ecc_engine() function while you
> > > hold the lock protecting the ECC engine list. And device_put() will be
> > > called in nand_put_hw_ecc_engine().    
> > 
> > 
> > I see.
> > 
> > Then I prefer keeping the logic in the core, not in the engine driver
> > and propose a
> > 
> >         void nand_ecc_put_engine(struct nand_ecc_engine *engine)
> > 
> > which will do nothing for on-die/sw engines and drop the reference for
> > hw engines. I will also rename the "find_ecc_engine" to "get_engine" so
> > that the call to the "put" helper has more meaning.  
> 
> Ack for most of it. One thing I'd like to clarify: it's probably better
> to have a separate function called nand_ecc_put_hw_engine() which you'll
> call from nand_ecc_put_engine() when you're dealing with an
> HW ECC engine rather than calling put_device() directly from
> nand_ecc_put_engine(). This way you keep the code for HW ECC engine
> well isolated.
> 
> Same goes for the nand_ecc_get_engine() path, just delegate to
> nand_ecc_get_hw_engine() when ->provider == HW_ECC.

Ack.

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