Subject: Re: MPC512x SPI very high cpu load

From: Matt Sealey <[email-masked]>
Date: Thu, 20 Nov 2008 13:39:54 -0600

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 <[email-masked]>
Genesi, Manager, Developer Relations