Re: [RFC 00/12] Marvell NAND controller rework with ->exec_op()

[Boris Brezillon <boris.brezillon@free-electrons.com>]

Hi Marc,

On Thu, 19 Oct 2017 10:47:07 +0200
Marc Gonzalez <marc_gonzalez@sigmadesigns.com> wrote:

> [ Dropping all mailing lists except linux-mtd ]
> 
> On 19/10/2017 00:29, Boris Brezillon wrote:
> 
> > Still need to review patch 6, but I'd like to say I'm really happy to
> > see that happen, finally. Hopefully that will help us make the NAND
> > framework a bit easier to maintain and allow us to support advanced
> > NAND features without having to patch all NAND controller drivers every
> > time we add a new vendor specific operation. I also have in mind a few
> > NAND controller drivers that have been rejected because they were not
> > fitting in the ->cmd_ctrl() approach and I didn't want to add more
> > drivers with their own partially implemented/broken ->cmdfunc() method.
> > 
> > Kudos for the work you've done, and I hope we'll get reviews from other
> > active NAND driver maintainers/contributors. To all NAND driver
> > maintainers: note that the long term goal is to get rid of  
> > ->cmd_ctrl()/cmdfunc()/read/write_buf/byte/word() entirely and replace  
> > them with a single ->exec_op() hook. Please let us know if you need
> > extra things that are not yet exposed in nand_op_instr/nand_op_parser
> > or if you would like things to be done differently.  
> 
> A long time ago, we discussed a limitation of the API for reads
> and writes handling only a single page at a time. My controller
> is able to "burst" 1-15 contiguous pages.
> 
> Does this rewrite help with such a feature, or is it orthogonal?

It's kind of orthogonal. To do what you want to do we'd need to extend
the current nand_chip/nand_ecc_ctrl interfaces to pass the MTD request
directly to the NAND controller driver and let it detect when a burst
access makes sense. Right now this is not my priority, but yes, I've
already thought a bit about how this interface would look like (see
this presentation [1] page 31).

Regards,

Boris

[1]https://events.linuxfoundation.org/sites/events/files/slides/brezillon-nand-framework_0.pdf