From: Ross Biro <rossb@google.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, Alan Cox <alan@redhat.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Linux 2.4.21-pre3-ac4
Date: Mon, 13 Jan 2003 10:49:49 -0800 [thread overview]
Message-ID: <3E230A4D.6020706@google.com> (raw)
In-Reply-To: 1042401074.525.219.camel@zion.wanadoo.fr
Benjamin Herrenschmidt wrote:
>On Sun, 2003-01-12 at 21:27, Alan Cox wrote:
>
>
>
>>which currently has two problems Ross found
>>
>>1. The processors or so fast we have to enforce the 400nS delay nowdays\
>>
The reason we need to enforce the 400nS delay is because of what is
going on on the other processor. If the other processor is in ide_intr
trying to grab the spinlock and we do not give the drive time to assert
the busy bit and the other processor makes it to the call to
drive_is_ready, then the drive could still return not busy and we could
think the command is done. This code path is probably less than 50
instructions, so I don't think it's taken anywhere near 400ns for a long
time.
DMA is slightly different. We don't actually have to delay the 400ns if
we call ide_dma_begin from inside the spinlock.
Ross
next prev parent reply other threads:[~2003-01-13 18:42 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-12 18:07 Linux 2.4.21-pre3-ac4 Alan Cox
2003-01-12 19:29 ` Benjamin Herrenschmidt
[not found] ` <1042403235.16288.14.camel@irongate.swansea.linux.org.uk>
2003-01-12 19:51 ` Benjamin Herrenschmidt
2003-01-12 19:57 ` Benjamin Herrenschmidt
2003-01-12 20:51 ` Alan Cox
2003-01-13 16:56 ` Benjamin Herrenschmidt
2003-01-12 20:40 ` Alan Cox
2003-01-12 20:02 ` Benjamin Herrenschmidt
2003-01-13 18:49 ` Ross Biro [this message]
2003-01-13 19:03 ` Benjamin Herrenschmidt
2003-01-13 19:19 ` Ross Biro
2003-01-13 19:32 ` Ross Biro
2003-01-13 21:05 ` Alan Cox
2003-01-13 20:36 ` Ross Biro
2003-01-13 19:46 ` Alan Cox
2003-01-14 17:38 ` Benjamin Herrenschmidt
2003-01-14 17:49 ` Ross Biro
2003-01-14 17:52 ` Benjamin Herrenschmidt
2003-01-14 21:17 ` Andre Hedrick
2003-01-15 0:23 ` Benjamin Herrenschmidt
2003-01-15 5:07 ` Andre Hedrick
[not found] ` <1043105473.12609.5.camel@dhcp22.swansea.linux.org.uk>
2003-01-21 17:07 ` Benjamin Herrenschmidt
2003-01-13 20:56 ` Benjamin Herrenschmidt
2003-01-13 21:36 ` Ross Biro
2003-01-14 1:35 ` Ross Biro
2003-01-14 1:44 ` Andre Hedrick
2003-01-14 9:18 ` Benjamin Herrenschmidt
2003-01-20 6:13 ` Alan Cox
2003-01-13 19:34 ` John Alvord
2003-01-13 19:48 ` Ross Biro
2003-01-13 21:24 ` Jeff Garzik
2003-01-13 21:40 ` Richard B. Johnson
2003-01-13 22:02 ` Benjamin Herrenschmidt
2003-01-13 22:07 ` Benjamin Herrenschmidt
2003-01-14 1:20 ` Richard B. Johnson
2003-01-14 9:06 ` Benjamin Herrenschmidt
2003-01-14 14:04 ` Richard B. Johnson
2003-01-14 14:35 ` Benjamin Herrenschmidt
2003-01-21 11:15 ` Linux 2.4.21-pre3-ac4 [PATCH] Paul Gortmaker
2003-01-21 13:21 ` Hugh Dickins
2003-01-21 11:46 ` small patch for Via Pro 266T agp-support Jurriaan
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