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From: Miquel Raynal <miquel.raynal@bootlin.com>
To: masonccyang@mxic.com.tw
Cc: vigneshr@ti.com, bbrezillon@kernel.org, juliensu@mxic.com.tw,
	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
	frieder.schrempf@kontron.de, marcel.ziswiler@toradex.com,
	Boris Brezillon <boris.brezillon@collabora.com>,
	linux-mtd@lists.infradead.org, richard@nod.at,
	tglx@linutronix.de, computersforpeace@gmail.com,
	dwmw2@infradead.org, marek.vasut@gmail.com
Subject: Re: [PATCH RFC 3/3] mtd: rawnand: Add support Macronix power down mode
Date: Tue, 15 Oct 2019 09:56:37 +0200	[thread overview]
Message-ID: <20191015095637.142e6db7@xps13> (raw)
In-Reply-To: <OF6D5429CF.876DE422-ON48258494.000D641F-48258494.000E0D4C@mxic.com.tw>

Hi Mason,

masonccyang@mxic.com.tw wrote on Tue, 15 Oct 2019 10:33:29 +0800:

> Hi Boris,
> 
>  
> > > > > +   nand_select_target(chip, 0);   
> > > > 
> > > > On several NAND controllers there is no way to act on the CS line
> > > > without actually writing bytes to the NAND chip. So basically this
> > > > is very likely to not work.   
> > > 
> > > any other way to make it work ? GPIO ?
> > > or just have some comments description here.
> > > i.e,.
> > > 
> > > /* The NAND chip will exit the deep power down mode with #CS toggling,   
> 
> > >  * please refer to datasheet for the timing requirement of tCRDP and   
> tRDP.
> > >  */
> > >   
> > 
> > Good luck with that. As Miquel said, on most NAND controllers
> > select_target() is a dummy operation that just assigns nand_chip->target
> > to the specified value but doesn't assert the CS line. You could send a
> > dummy command here, like a READ_ID, but I guess you need CS to be
> > asserted for at least 20ns before asserting any other signals (CLE/ALE)
> > which might be an issue.  
> 
> okay, got it.
> But if possible, I think adding CS line control in nand_select_target()
> is a simple and generic way for MTD and all raw NAND controllers.

The problem is not that we do not want to; the problem is that
controllers are not capable of doing it reliably if no byte is sent
over the NAND bus.


Thanks,
Miquèl

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/

WARNING: multiple messages have this Message-ID (diff)
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: masonccyang@mxic.com.tw
Cc: "Boris Brezillon" <boris.brezillon@collabora.com>,
	bbrezillon@kernel.org, computersforpeace@gmail.com,
	dwmw2@infradead.org, frieder.schrempf@kontron.de,
	gregkh@linuxfoundation.org, juliensu@mxic.com.tw,
	linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org,
	marcel.ziswiler@toradex.com, marek.vasut@gmail.com,
	richard@nod.at, tglx@linutronix.de, vigneshr@ti.com
Subject: Re: [PATCH RFC 3/3] mtd: rawnand: Add support Macronix power down mode
Date: Tue, 15 Oct 2019 09:56:37 +0200	[thread overview]
Message-ID: <20191015095637.142e6db7@xps13> (raw)
In-Reply-To: <OF6D5429CF.876DE422-ON48258494.000D641F-48258494.000E0D4C@mxic.com.tw>

Hi Mason,

masonccyang@mxic.com.tw wrote on Tue, 15 Oct 2019 10:33:29 +0800:

> Hi Boris,
> 
>  
> > > > > +   nand_select_target(chip, 0);   
> > > > 
> > > > On several NAND controllers there is no way to act on the CS line
> > > > without actually writing bytes to the NAND chip. So basically this
> > > > is very likely to not work.   
> > > 
> > > any other way to make it work ? GPIO ?
> > > or just have some comments description here.
> > > i.e,.
> > > 
> > > /* The NAND chip will exit the deep power down mode with #CS toggling,   
> 
> > >  * please refer to datasheet for the timing requirement of tCRDP and   
> tRDP.
> > >  */
> > >   
> > 
> > Good luck with that. As Miquel said, on most NAND controllers
> > select_target() is a dummy operation that just assigns nand_chip->target
> > to the specified value but doesn't assert the CS line. You could send a
> > dummy command here, like a READ_ID, but I guess you need CS to be
> > asserted for at least 20ns before asserting any other signals (CLE/ALE)
> > which might be an issue.  
> 
> okay, got it.
> But if possible, I think adding CS line control in nand_select_target()
> is a simple and generic way for MTD and all raw NAND controllers.

The problem is not that we do not want to; the problem is that
controllers are not capable of doing it reliably if no byte is sent
over the NAND bus.


Thanks,
Miquèl

  reply	other threads:[~2019-10-15  7:57 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-18  7:56 [PATCH RFC 1/3] mtd: rawnand: Add support manufacturer postponed initialization Mason Yang
2019-09-18  7:56 ` Mason Yang
2019-09-18  7:56 ` [PATCH RFC 2/3] mtd: rawnand: Add support Macronix Block Protection function Mason Yang
2019-09-18  7:56   ` Mason Yang
2019-10-07  8:45   ` Miquel Raynal
2019-10-07  8:45     ` Miquel Raynal
2019-10-07  9:24     ` Miquel Raynal
2019-10-07  9:24       ` Miquel Raynal
2019-10-08  2:33       ` masonccyang
2019-10-08  2:33         ` masonccyang
2019-10-08 15:02         ` Miquel Raynal
2019-10-08 15:02           ` Miquel Raynal
2019-10-15  6:47           ` masonccyang
2019-10-15  6:47             ` masonccyang
     [not found]           ` <OFB4F10613.467EB346-ON48258494.0020403E-48258494.002550A2@LocalDomain>
2019-10-21  7:23             ` masonccyang
2019-10-21  7:23               ` masonccyang
2019-10-21  7:44               ` Boris Brezillon
2019-10-21  7:44                 ` Boris Brezillon
2019-10-21  8:40                 ` masonccyang
2019-10-21  8:40                   ` masonccyang
2019-10-21  8:56                   ` Boris Brezillon
2019-10-21  8:56                     ` Boris Brezillon
2019-10-21  9:07                     ` masonccyang
2019-10-21  9:07                       ` masonccyang
2019-09-18  7:56 ` [PATCH RFC 3/3] mtd: rawnand: Add support Macronix power down mode Mason Yang
2019-09-18  7:56   ` Mason Yang
2019-10-07  8:45   ` Miquel Raynal
2019-10-07  8:45     ` Miquel Raynal
2019-10-08  2:06     ` masonccyang
2019-10-08  2:06       ` masonccyang
2019-10-08  7:28       ` Boris Brezillon
2019-10-08  7:28         ` Boris Brezillon
2019-10-15  2:33         ` masonccyang
2019-10-15  2:33           ` masonccyang
2019-10-15  7:56           ` Miquel Raynal [this message]
2019-10-15  7:56             ` Miquel Raynal
2019-10-16  6:55             ` masonccyang
2019-10-16  6:55               ` masonccyang
2019-10-25  3:11         ` masonccyang
2019-10-25  3:11           ` masonccyang

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