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From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
	linux-ide@vger.kernel.org, akpm@osdl.org
Subject: Re: [PATCH] libata-core: Don't have screaming fits over DF/ERR combinations
Date: Tue, 16 Oct 2007 00:05:53 +0400	[thread overview]
Message-ID: <4713C821.6090303@ru.mvista.com> (raw)
In-Reply-To: <4713C74F.3020205@pobox.com>

Jeff Garzik wrote:

>>> Some hardware seems to get this wrong in a non-harmful way, and there 
>>> are
>>> some devices that seem to do it deliberately for various reasons.

>>> Just take it as a device error not a catastrophic state machine
>>> explosion. 

>>> Signed-off-by: Alan Cox <alan@redhat.com>

>>> diff -u --exclude-from /usr/src/exclude --new-file --recursive 
>>> linux.vanilla-2.6.23-mm1/drivers/ata/libata-core.c 
>>> linux-2.6.23-mm1/drivers/ata/libata-core.c
>>> --- linux.vanilla-2.6.23-mm1/drivers/ata/libata-core.c    2007-10-15 
>>> 15:03:26.000000000 +0100
>>> +++ linux-2.6.23-mm1/drivers/ata/libata-core.c    2007-10-15 
>>> 15:13:49.000000000 +0100
>>> @@ -5258,7 +5319,15 @@
>>>          if (unlikely(status & (ATA_ERR | ATA_DF))) {
>>>              ata_port_printk(ap, KERN_WARNING, "DRQ=1 with device "
>>>                      "error, dev_stat 0x%X\n", status);
>>> -            qc->err_mask |= AC_ERR_HSM;
>>> +            /* Some devices muck this up. Some follow an ATA
>>> +               non-standard that permits the damaged sector to
>>> +               be retrieved at this point. The ATA spec says
>>> +               we should jump up and down on DRQ + ERR, reality

>>    I've always thought that setting both DRQ and ERR is perfectly 
>> valid (well, maybe it's become invalid since ATAPI-4 where all these 
>> state transition flow charts have made its first appearance, to be 
>> quickly replaced by the state diagrams :-) -- I'm too lazy to check 
>> now... :-)

> DRQ+ERR is valid, and SRST (or hard reset) is defined as the method of 
> kicking the device out of that state.

    Well, in the times of old, reading a sector (or group of them for multiple 
mode) was valid for that purpose, wasn't it?

>     Jeff

MBR, Sergei

  reply	other threads:[~2007-10-15 20:05 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-15 18:23 [PATCH] libata-core: Don't have screaming fits over DF/ERR combinations Alan Cox
2007-10-15 19:53 ` Sergei Shtylyov
2007-10-15 20:02   ` Jeff Garzik
2007-10-15 20:05     ` Sergei Shtylyov [this message]
2007-10-15 20:09       ` Jeff Garzik
2007-10-15 20:58         ` Alan Cox
2007-10-25  6:04 ` Jeff Garzik

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