From: Mark Lord <liml@rtr.ca>
To: Mat.Loikkanen@synopsys.com
Cc: 'Jeff Garzik' <jgarzik@pobox.com>, linux-ide@vger.kernel.org
Subject: Re: data_xfer too fast? - SATA PIO
Date: Mon, 28 Feb 2005 22:06:45 -0500 [thread overview]
Message-ID: <4223DC45.9000204@rtr.ca> (raw)
In-Reply-To: <00dc01c51dee$c2cf13a0$3805040a@internal.synopsys.com>
Err.. PIO data transfer within a sector (or multiple sector block)
is supposed to be synchronous in hardware. This means the chip/board
should be using IORDY to stretch the cycle until data can be supplied
within each 256-word interrupt group.
Right?
Mat Loikkanen wrote:
> We've run into the issue of ata_mmio_data_xfer() reading our host
> controller's data fifo too fast -- requesting a data word when the fifo was
> empty, before the device had sent PIO data (in our observed case somewhere
> in the middle of a 512 byte IDENTIFY DEVICE PIO data transfer). I can't see
> any provision in Libata for a case like ours where the processor and bus are
> "too fast". Has anyone run into this issue before? Any ideas on what we
> should do about it? We can make our host controller to wait-state the bus
> ... but for how long, what if data never arrives ... Thanks for any help.
>
> -mat
>
> Mat Loikkanen
> Synopsys, Inc.
next prev parent reply other threads:[~2005-03-01 3:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-28 23:39 data_xfer too fast? - SATA PIO Mat Loikkanen
2005-03-01 3:06 ` Mark Lord [this message]
2005-03-01 17:49 ` Mat Loikkanen
2005-03-02 1:44 ` Benjamin Herrenschmidt
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