From: Krzysztof Halasa <khc@pm.waw.pl>
To: Arjan van de Ven <arjan@infradead.org>
Cc: "Lennart Baruschka" <FunFlyer@gmx.net>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel@vger.kernel.org
Subject: Re: Disabling DMA with ICH10?
Date: Tue, 29 Sep 2009 14:29:27 +0200 [thread overview]
Message-ID: <m3bpku3peg.fsf@intrepid.localdomain> (raw)
In-Reply-To: <20090929101114.1712314b@infradead.org> (Arjan van de Ven's message of "Tue, 29 Sep 2009 10:11:14 +0200")
Arjan van de Ven <arjan@infradead.org> writes:
> a single PIO instruction will NOT be interrupted by an interrupt.
> And can easily take several microseconds (remember: 8Mhz bus
> emulation)
Not that long, there is no emulation there (except for port #80 (hex?)
and similar). Normal 33 MHz access. But it's still slow, of course -
every access takes at least 4(?) bus cycles (IIRC: address, initiator
ready, device selected, target ready). No bursts (at least on typical
x86 hw).
Of course ICH10 AHCI isn't connected with PCI 33/32 bus.
Anyway: PIO = bad idea.
--
Krzysztof Halasa
next prev parent reply other threads:[~2009-09-29 12:29 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-28 21:31 Disabling DMA with ICH10? Lennart Baruschka
2009-09-28 20:37 ` Alejandro Riveira Fernández
2009-09-28 22:40 ` Alan Cox
2009-09-29 7:54 ` Lennart Baruschka
2009-09-29 8:11 ` Arjan van de Ven
2009-09-29 12:29 ` Krzysztof Halasa [this message]
2009-09-29 17:05 ` Alan Cox
2009-09-29 20:35 ` Krzysztof Halasa
2009-09-29 22:35 ` Alan Cox
2009-09-30 12:21 ` Krzysztof Halasa
2009-09-29 10:46 ` Alan Cox
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