Hi Mason,
masonccy...@mxic.com.tw wrote on Wed, 19 Jun 2019 16:04:43 +0800:
> 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.brezil...@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.
>
We really need to see the datasheet of the NAND chip which has a
problem and how this LPM mode is advertized to understand what the
chip expects and eventually how to work-around it.
> 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()
Yes, this is expected and usually chips don't care.
> and
> driver will get incorrect ONFI parameter table data from
> nand_read_data_op().
>
Thanks,
Miquèl
