From: Gernot Hoyler <Gernot.Hoyler@spansion.com>
To: qzhan2009@gmail.com
Cc: linux-mtd@lists.infradead.org
Subject: Re: Re: Anyone can help me about do_write_buffer at cfi_cmdset_0002
Date: Thu, 9 Sep 2010 14:38:21 +0200 [thread overview]
Message-ID: <4C88D53D.1070109@spansion.com> (raw)
In-Reply-To: <AANLkTi=vYL2uAycRoaBW3cG5EHb_FU3sYcP=899ouHuK@mail.gmail.com>
> In functions
> do_write_buffer @ drivers/mtd/chips/cfi_cmdset_0002.c.
> /* why word_write_time? */
I assume this is because the write times as given by CFI are typical times and
is most cases the device is faster than that. In other words, if we waited
"buffer_write_time" before starting to poll then the device would already have
finished the operation and we would waste time in most cases.
Actually, newer devices would work without any delay after sending the command
cycles and before polling. However, first generation MirrorBit devices (-A and
-M families) required a 4us delay to give stable status information. So
waiting the typical word program time is a good compromise. It gives you
maximum performance while still keeping compatiblility with older devices.
--Gernot
prev parent reply other threads:[~2010-09-09 12:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-08 1:18 Anyone can help me about do_write_buffer at cfi_cmdset_0002 Qi Zhang
2010-09-09 12:38 ` Gernot Hoyler [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4C88D53D.1070109@spansion.com \
--to=gernot.hoyler@spansion.com \
--cc=linux-mtd@lists.infradead.org \
--cc=qzhan2009@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).