From: Matt Sealey <matt@genesi-usa.com>
To: Matteo Fortini <m.fortini@selcomgroup.com>
Cc: linuxppc-embedded@ozlabs.org
Subject: Re: MPC512x SPI very high cpu load
Date: Thu, 20 Nov 2008 13:39:54 -0600 [thread overview]
Message-ID: <4925BD0A.3030307@genesi-usa.com> (raw)
In-Reply-To: <49243010.9070106@selcomgroup.com>
Matteo Fortini wrote:
> Hi,
> we're using the latest denx tree on an mpc512x, and we have a
> touchscreen on the spi which is talking at 100kHz.
>
> The polling frequency is 5ms and we transmit around 20 bytes per poll.
>
> If we keep the touchscreen pressed, cpu utilization goes to 70% for the
> spi task. This is quite strange, since I thought the mpc512x would be
> using DMA to feed the PSC FIFOs.
If the SPI driver isn't using DMA then, it's not using DMA.
--
Matt Sealey <matt@genesi-usa.com>
Genesi, Manager, Developer Relations
prev parent reply other threads:[~2008-11-20 19:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-19 15:26 MPC512x SPI very high cpu load Matteo Fortini
2008-11-20 19:39 ` Matt Sealey [this message]
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