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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



  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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