From: Sylvain Munaut <tnt@246tNt•com>
To: roman.kuzmenko@auriga•ru
Cc: Linuxppc-embedded <Linuxppc-embedded@ozlabs•org>
Subject: Re: MPC5200, PCI, udelay(10)
Date: Sat, 04 Feb 2006 11:51:14 +0100 [thread overview]
Message-ID: <43E48722.8060103@246tNt.com> (raw)
In-Reply-To: <1137745904.4631.17.camel@trust.auriga.ru>
Roman Kuzmenko wrote:
> Hello.
>
> Please, help me to investigate why the delays present in the
> "mpc5xxx_read_config_dword" and "mpc5xxx_write_config_dword" functions
> in the "arch/ppc/kernel/mpc52xx_pci.c" file.
>
> I.e.
> ==========================
> *(volatile u32 *)MPC5xxx_PCI_CAR = 0;
>
>>udelay(10);
>
> return 0;
> ==========================
>
> I was neither able to find any reference at the MPC5200 documentation
> supplied by FreeScale nor reproduce any error with these lines got
> removed.
I wasn't able to reproduce any problem either but people kept reporting
problems. But it seems that it's not a delay that's needed but a mb() to
ensure the write all _completly_ done before the next write. A
udelay(10) almost ensure that also but is a lot less elegant imho.
Sylvain
prev parent reply other threads:[~2006-02-04 10:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-20 8:31 MPC5200, PCI, udelay(10) Roman Kuzmenko
2006-01-20 17:24 ` Andrey Volkov
2006-02-04 10:51 ` Sylvain Munaut [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=43E48722.8060103@246tNt.com \
--to=tnt@246tnt$(echo .)com \
--cc=Linuxppc-embedded@ozlabs$(echo .)org \
--cc=roman.kuzmenko@auriga$(echo .)ru \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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