From: "Burkhard Schölpen" <bschoelpen@web.de>
To: PaulFulghum <paulkf@microgate.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: PCI DMA burst delay
Date: Thu, 29 Dec 2005 17:03:12 +0100 [thread overview]
Message-ID: <395603262@web.de> (raw)
>Paul Fulghum <paulkf@microgate.com> schrieb am 29.12.05 16:30:20:
>
>Burkhard Schölpen wrote:
>> ... in the (rarely) faulty case, the 2nd burst only starts
>> after another delay of about 600ns, which is too late
>
>Looking at the PCI 2.3 specification,
>arbitration latency on the order of a microsecond
>or two does not seem excessive for a 33MHz bus.
Okay, then I think I have to figure out, why I cannot get longer bursts than 512 Bits...does anybody have a clue how I can handle that?
>> ... I deactivated all other pci devices that could disturb the transfers?
>
>Are you accessing registers on your device
>during the DMA transfers? If so, the CPU is
>acting as a PCI master that could delay granting
>the bus to your device.
No, I just made sure that not. There are no register accesses during dma transfer. The driver sends the application to sleep until an interrupt signals the completeness.
Kind regards,
Burkhard
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next reply other threads:[~2005-12-29 16:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-29 16:03 Burkhard Schölpen [this message]
2005-12-29 16:55 ` PCI DMA burst delay Paul Fulghum
-- strict thread matches above, loose matches on Subject: below --
2005-12-30 13:23 Burkhard Schölpen
2005-12-30 18:45 ` Robert Hancock
[not found] <5p7gt-3lu-5@gated-at.bofh.it>
2005-12-29 18:40 ` Robert Hancock
2005-12-29 14:43 Burkhard Schölpen
2005-12-29 15:23 ` Paul Fulghum
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