[PATCH 1/2] mtd: nand: Check ONFI timings have been acked by the chip

[Boris Brezillon]

On Mon, 15 Jan 2018 17:57:08 +0000
Han Xu <han.xu at nxp.com> wrote:

> ________________________________________
> From: Boris Brezillon <boris.brezillon at free-electrons.com>
> Sent: Monday, January 15, 2018 7:19 AM
> To: Han Xu
> Cc: Miquel RAYNAL; Richard Weinberger; David Woodhouse; Brian Norris; Marek Vasut; Cyrille Pitchen; linux-mtd at lists.infradead.org
> Subject: Re: [PATCH 1/2] mtd: nand: Check ONFI timings have been acked by the chip
> 
> Hi Han,
> 
> On Mon, 8 Jan 2018 14:04:29 +0100
> Boris Brezillon <boris.brezillon at free-electrons.com> wrote:
> 
> > On Fri, 5 Jan 2018 16:42:39 +0100
> > Miquel RAYNAL <miquel.raynal at free-electrons.com> wrote:
> >  
> > > Hello,
> > >  
> > > > Hm, I'm not sure this is safe. The spec says that new ONFI timing mode
> > > > is applied as soon the CS line is released after a
> > > > SET_FEATURES(ONFI_FEATURE_ADDR_TIMING_MODE), and since we have no
> > > > guarantee that the CS will be kept low by the controller after  
> > > > ->onfi_set_features() returns we must assume the new mode has been  
> > > > applied and call ->setup_data_interface() to instruct the controller
> > > > to apply new timings.
> > > >
> > > > If you want to check if the mode has really been applied, you should
> > > > release the CS (->select_chip(-1)), re-acquire it
> > > > (->select_chip(X)), and call  
> > > > ->onfi_get_features(ONFI_FEATURE_ADDR_TIMING_MODE). If it appears  
> > > > that the mode has not been applied, you should restore timing mode 0
> > > > and issue a RESET.  
> > >
> > > Boris, thanks for the comment, I will fix that.
> > >
> > > Han, could I have your input on this series? Aside Boris' comment of
> > > course.  
> >
> > Han, we really need your feedback on this series since you were the one
> > complaining that ONFI mode should be checked back after applying a new
> > mode. Miquel is reworking the framework to mimic what the GPMI driver,
> > but we need to be sure that you'll accept to transition to the generic  
> > ->setup_data_interface() solution.  
> 
> Thanks Miquel, I do accept to transit to setup_data_interface solution and actually
> I am also working on the similar patches. I reviewed the patch set and don't have
> more comments, this one improved more than mine.

Glad to hear you're not opposed to the idea.