From: Mark Lord <liml@rtr.ca>
To: albertl@mail.com
Cc: Jeff Garzik <jgarzik@pobox.com>,
IDE Linux <linux-ide@vger.kernel.org>,
Tejun Heo <htejun@gmail.com>, Doug Maxey <dwm@maxeymade.com>
Subject: Re: [PATCH 1/1] libata-dev: ata_check_atapi_dma() fix for ATA_FLAG_PIO_POLLING LLDDs
Date: Wed, 15 Mar 2006 11:24:39 -0500 [thread overview]
Message-ID: <44183FC7.3020401@rtr.ca> (raw)
In-Reply-To: <44183CDA.5010407@rtr.ca>
Mark Lord wrote:
> Albert Lee wrote:
>> Jeff Garzik wrote:
>>
>>> Applied, though I think its an open question what happens with
>>> CDB-interrupt ATAPI devices want to do DMA. Perhaps we just get an
>>> interrupt event that we clear, then life proceeds as normal.
Oh yeah, from experience I know that the interrupt and DRQ bit
are *NOT* synchronized with these devices.. I believe that the IRQ
sometimes arrives early, and sometimes late.
Reading the ATA status reg after the IRQ always clears the IRQ,
and is usually necessary for the transfer to continue.
The last time I did a full ATAPI driver, it used both periodic polling
and an IRQ handler to wait for (DRQ && !BUSY).
Cheers
next prev parent reply other threads:[~2006-03-15 16:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-13 7:57 [PATCH 1/1] libata-dev: ata_check_atapi_dma() fix for ATA_FLAG_PIO_POLLING LLDDs Albert Lee
2006-03-13 8:09 ` Jeff Garzik
2006-03-14 4:52 ` Albert Lee
2006-03-15 15:54 ` Mark Lord
2006-03-15 16:12 ` Mark Lord
2006-03-15 16:24 ` Mark Lord [this message]
2006-03-16 7:22 ` Albert Lee
2006-03-17 5:51 ` Mark Lord
2006-03-15 16:49 ` Mark Lord
2006-04-01 13:24 ` Albert Lee
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