From: Mark Mason <mason@postdiluvian.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: MPC831x (and others?) NAND erase performance improvements
Date: Tue, 7 Dec 2010 13:23:17 -0500 [thread overview]
Message-ID: <20101207182317.GA23155@postdiluvian.org> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6D8ABEB@saturn3.aculab.com>
David Laight <David.Laight@ACULAB.COM> wrote:
> > The problem cropped up when there was a lot of traffic to the NAND
> > (Samsung K9WAGU08U1B-PIB0), with the NAND being on the LBC along with
> > a video chip that needed constant and prompt attention.
> >
> > What I would see is that, as the writes happened, the erases would
> > wind up batched and issued all at once, such that frequently 400-700
> > erases were issued in rapid succession with a 1ms LBC BUSY cycle per
> > erase.
>
> Are those just the reads of the status register polling to
> determine when the sector erase has completed ?
No, it's not, since it isn't polling the status register. It's using
a hardware line from the NAND to indicate that the NAND is busy. That
one hardware line is shared between all devices on the bus, so if one
device says it's busy then all bus traffic stops until the NAND
deasserts the busy line.
next prev parent reply other threads:[~2010-12-07 18:23 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-07 3:15 MPC831x (and others?) NAND erase performance improvements Mark Mason
2010-12-07 9:00 ` David Laight
2010-12-07 18:23 ` Mark Mason [this message]
2010-12-07 20:51 ` Scott Wood
2010-12-07 23:24 ` Mark Mason
2010-12-08 0:37 ` Scott Wood
2010-12-08 7:59 ` Joakim Tjernlund
2010-12-08 17:18 ` Scott Wood
2010-12-08 17:32 ` Joakim Tjernlund
2010-12-08 19:26 ` Mark Mason
2010-12-08 19:57 ` Joakim Tjernlund
2010-12-08 19:59 ` Scott Wood
2010-12-08 20:11 ` Joakim Tjernlund
2010-12-08 20:25 ` Scott Wood
2010-12-08 21:26 ` Joakim Tjernlund
2010-12-08 22:02 ` Mark Mason
2010-12-08 22:25 ` Scott Wood
2010-12-09 0:16 ` Joakim Tjernlund
2010-12-10 12:39 ` Joakim Tjernlund
2010-12-10 17:56 ` Scott Wood
2010-12-11 9:14 ` Joakim Tjernlund
2010-12-13 8:33 ` David Laight
2010-12-13 10:32 ` Joakim Tjernlund
2010-12-13 17:33 ` Scott Wood
2010-12-13 17:41 ` Joakim Tjernlund
2010-12-13 17:51 ` Scott Wood
2010-12-13 19:30 ` Joakim Tjernlund
2010-12-13 19:49 ` Scott Wood
2010-12-13 22:28 ` Joakim Tjernlund
2010-12-08 22:05 ` Scott Wood
2010-12-10 8:47 ` Andre Schwarz
2010-12-10 8:56 ` Joakim Tjernlund
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