From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Mat.Loikkanen@synopsys.com
Cc: 'Jeff Garzik' <jgarzik@pobox.com>,
list linux-ide <linux-ide@vger.kernel.org>
Subject: Re: data_xfer too fast? - SATA PIO
Date: Wed, 02 Mar 2005 12:44:43 +1100 [thread overview]
Message-ID: <1109727883.5680.73.camel@gaston> (raw)
In-Reply-To: <00dc01c51dee$c2cf13a0$3805040a@internal.synopsys.com>
On Mon, 2005-02-28 at 15:39 -0800, 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.
>
You should waitstate the bus, with eventually some sanity limit built
into the HW.
Ben.
prev parent reply other threads:[~2005-03-02 1:47 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
2005-03-01 17:49 ` Mat Loikkanen
2005-03-02 1:44 ` Benjamin Herrenschmidt [this message]
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