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

[masonccyang]

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@xxxxxxxxxxxxx> 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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