Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND controller

masonccyang
2019-06-19T08:04:49Z

Hi Boris,

>
> Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND controller
>
> On Tue, 18 Jun 2019 08:14:36 +0200
> Boris Brezillon <boris.brezillon@collabora.com> wrote:
>
> > > > > > >
> > > > > > > How to make all #CS keep high for NAND to enter
> > > > > > > low-power standby mode if driver don't use
"legacy.select_chip()"
> > > ?
> > > > > >
> > > > > > See commit 02b4a52604a4 ("mtd: rawnand: Make ->select_chip()
> > > optional
> > > > > > when ->exec_op() is implemented") which states:
> > > > > >
> > > > > > "When [->select_chip() is] not implemented, the core
is
> > > assuming
> > > > > > the CS line is automatically asserted/deasserted by the
driver
> > > > > > ->exec_op() implementation."
> > > > > >
> > > > > > Of course, the above is right only when the controller driver

> > > supports
> > > > > > the ->exec_op() interface.
> > > > >
> > > > > Currently, it seems that we will get the incorrect data and
error
> > > > > operation due to CS in error toggling if CS line is controlled
in
> > > > > ->exec_op().
>
> Oh, and please provide the modifications you added on top of this patch.
> Right now we're speculating on what you've done which is definitely not
> an efficient way to debug this sort of issues.

The patch is to add in beginning of ->exec_op() to control CS# low and
before return from ->exec_op() to control CS# High.
i.e,.
static in mxic_nand_exec_op( )
{
cs_to_low();

cs_to_high();
return;
}

But for nand_onfi_detect(),
it calls nand_read_param_page_op() and then nand_read_data_op().
mxic_nand_exec_op() be called twice for nand_onfi_detect() and
driver will get incorrect ONFI parameter table data from
nand_read_data_op().

thanks & best regards,
Mason

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