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

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Message-ID: <OF5EAF94EB.AE31CF59-ON4825841E.002A2C38-4825841E.002C60BF@mxic.com.tw>
Date:   Wed, 19 Jun 2019 16:04:43 +0800
From:   masonccyang@...c.com.tw
To:     "Boris Brezillon" <boris.brezillon@...labora.com>
Cc:     bbrezillon@...nel.org, broonie@...nel.org,
        christophe.kerello@...com, computersforpeace@...il.com,
        devicetree@...r.kernel.org, dwmw2@...radead.org,
        geert@...ux-m68k.org, juliensu@...c.com.tw, lee.jones@...aro.org,
        liang.yang@...ogic.com, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-spi@...r.kernel.org,
        marcel.ziswiler@...adex.com, marek.vasut@...il.com,
        mark.rutland@....com, "Miquel Raynal" <miquel.raynal@...tlin.com>,
        paul.burton@...s.com, richard@....at, robh+dt@...nel.org,
        stefan@...er.ch, zhengxunli@...c.com.tw
Subject: Re: [PATCH v3 2/4] mtd: rawnand: Add Macronix MX25F0A NAND controller

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@...labora.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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CONFIDENTIALITY NOTE:

This e-mail and any attachments may contain confidential information and/or personal data, which is protected by applicable laws. Please be reminded that duplication, disclosure, distribution, or use of this e-mail (and/or its attachments) or any part thereof is prohibited. If you receive this e-mail in error, please notify us immediately and delete this mail as well as its attachment(s) from your system. In addition, please be informed that collection, processing, and/or use of personal data is prohibited unless expressly permitted by personal data protection laws. Thank you for your attention and cooperation.

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