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
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http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply other threads:[~2019-10-15 7:57 UTC|newest]
Thread overview: 20+ 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 ` [PATCH RFC 2/3] mtd: rawnand: Add support Macronix Block Protection function Mason Yang
2019-10-07 8:45 ` Miquel Raynal
2019-10-07 9:24 ` Miquel Raynal
2019-10-08 2:33 ` masonccyang
2019-10-08 15:02 ` Miquel Raynal
2019-10-15 6:47 ` masonccyang
[not found] ` <OFB4F10613.467EB346-ON48258494.0020403E-48258494.002550A2@LocalDomain>
2019-10-21 7:23 ` masonccyang
2019-10-21 7:44 ` Boris Brezillon
2019-10-21 8:40 ` masonccyang
2019-10-21 8:56 ` Boris Brezillon
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
2019-10-07 8:45 ` Miquel Raynal
2019-10-08 2:06 ` masonccyang
2019-10-08 7:28 ` Boris Brezillon
2019-10-15 2:33 ` masonccyang
2019-10-15 7:56 ` Miquel Raynal [this message]
2019-10-16 6:55 ` masonccyang
2019-10-25 3:11 ` masonccyang
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