From: Mark Lord <mlord@pobox.com>
To: Tejun Heo <htejun@gmail.com>
Cc: Art Haas <ahaas@airmail.net>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-ide@vger.kernel.org, Albert Lee <albertcc@tw.ibm.com>,
Sergei Shtylyov <sshtylyov@ru.mvista.com>
Subject: Re: [PATCH] ata_piix: fix pio/mwdma programming (for testing, don't apply)
Date: Sat, 03 Feb 2007 14:47:07 -0500 [thread overview]
Message-ID: <45C4E6BB.6020307@pobox.com> (raw)
In-Reply-To: <45C3EECF.2080100@gmail.com>
Tejun Heo wrote:
> ..
> Then, PACKET_IDENTIFY after configuring transfer mode fails with
> -ENOENT. Meaning it saw (status & (ATA_BUSY|ATA_DRQ|ATA_ERR|ATA_DF)) ==
> 0 in HSM_ST.
..
> So, PATA gurus, can you bless us with enlightenment? :-)
Heh.. guaranteeing detection of all the strange implementations out there
is part black magic.
But the simple thing to do here is, just for fun, hack the code
to do the infamous 50 millisecond hard wait before issuing the PACKET_IDENTIFY.
If that fixes it, then it's just a matter of tuning to discover the real
amount of delay required, and a nicer way of doing the delay.
Also, zero out the features register before issuing PACKET_IDENTIFY,
if the code isn't already doing that.
After the drive asserts BUSY, and later deasserts BUSY,
there might be a slight delay before the drive asserts DRQ.
So, it is possible for the status to read zeros in the important bits.
My suggestion is to wait up to the infamous 50 milliseconds again here,
if needed.
????
Cheers
--
Mark Lord
Real-Time Remedies Inc.
mlord@pobox.com
next prev parent reply other threads:[~2007-02-03 20:10 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-02 15:18 [PATCH] ata_piix: fix pio/mwdma programming (for testing, don't apply) Tejun Heo
2007-02-02 15:34 ` Sergei Shtylyov
2007-02-02 16:38 ` Jeff Garzik
2007-02-02 16:57 ` Mark Lord
2007-02-02 18:34 ` Sergei Shtylyov
2007-02-02 16:41 ` Tejun Heo
2007-02-02 18:49 ` Alan
2007-02-02 19:04 ` Sergei Shtylyov
2007-02-02 17:42 ` Alan
2007-02-03 1:40 ` Tejun Heo
2007-02-03 20:04 ` Alan
2007-02-04 2:47 ` Tejun Heo
2007-02-02 21:14 ` Art Haas
2007-02-03 2:09 ` Tejun Heo
2007-02-03 14:35 ` Art Haas
2007-02-03 19:47 ` Mark Lord [this message]
2007-02-06 9:11 ` Tejun Heo
2007-02-06 16:33 ` Art Haas
2007-02-07 2:53 ` Tejun Heo
2007-02-07 19:35 ` Art Haas
2007-02-07 19:51 ` Mark Lord
2007-02-07 20:37 ` [PATCH] libata: clear TF before IDENTIFYing Tejun Heo
2007-02-08 14:56 ` Mark Lord
2007-02-13 19:38 ` Art Haas
2007-02-15 23:08 ` Jeff Garzik
2007-04-30 18:29 ` [PATCH] Fix pio/mwdma programming on ata_piix.c Art Haas
2007-05-01 3:02 ` Tejun Heo
2007-05-24 19:59 ` Art Haas
2007-05-24 20:55 ` Jeff Garzik
2007-05-24 21:03 ` Tejun Heo
2007-05-25 17:16 ` [PATCH] ata_piix: fix pio/mwdma programming Tejun Heo
2007-05-25 18:05 ` Alan Cox
2007-05-28 13:02 ` Jeff Garzik
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