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

[Miquel Raynal]

Hi Han,

On Mon, 15 Jan 2018 19:41:08 +0100
Boris Brezillon <boris.brezillon at free-electrons.com> wrote:

> 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.

I'm happy to read this, I'll send a v2 tomorrow that addresses Boris'
comments.

Thanks,
Miquèl