[PATCH v10 04/10] mtd: nand: omap: fix device scan: NAND_CMD_READID, NAND_CMD_RESET, CMD_CMD_PARAM use only x8 bus

[Ezequiel Garcia]

Brian,

On Tue, Oct 22, 2013 at 11:13:32PM -0700, Brian Norris wrote:
> On 10/22/2013 10:07 PM, Gupta, Pekon wrote:
> >> From: Brian Norris [mailto:computersforpeace at gmail.com]
> >> On Sat, Oct 19, 2013 at 02:14:08PM +0530, Pekon Gupta wrote:
> > [...]
> > 
> >>>
> >>> Thus this patch run nand_scan_ident() with driver configured as x8 device.
> >>
> >> So are you saying that the driver currently doesn't work if you started
> >> in x16 buswidth? Are you having problems with a particular setup? What
> >> sort of devices are you testing?
> >>
> > No, I'm saying that you cannot read ONFI params in x16 mode.
> > And, that is what was pointed out in following commit log also ..
> > (Reference to 3.3.2. Target Initialization: given above)
> > So, if I run nand_scan_ident() in x16 mode, my ONFI detection would 
> > fail for sure ..
> 
> But you cannot just run nand_scan_ident() with !(chip->options &
> NAND_BUSWIDTH_16) when your devices is x16. You need to solve the ONFI
> detection problem while correctly specifying NAND_BUSWIDTH_16.
> 
> Since you didn't answer the other 2 questions there: are you testing any
> x16 devices?
> 

I'm jumping on this thread without having read all the discussion, sorry
about that.

FWIW, I have a Beaglebone with a 16-bit bus NAND attached to it.

Coincidentally, yesterday I was doing some tests as I'm ramping up the
NAND and I found that weird double nand_scan_ident() call.
The whole thing looks buggy to me, so I'm happy to help, review, test
and patches to take care of this.

I'm using some TI SDK with some ancient v3.2.x (with no git history!),
but from this discussion it seems the issue is still present in
mainline.
-- 
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com