IDMAC interference with other DMA sources

[paul_h]

Hi there,

I currently have some trouble with my camera. I'm workin' with a iMX35 and I would like to stream pictures from a camera to the foreground layer of the IPU.

I'm using Windows CE 6 R3 and the Freescale standard IPU driver. I've set the direct display option in order to get the camera pictures directly transferred via IDMAC to the foreground (over SDC). Basically the transfer works. The camera input is being shown on my device. However, if the target resolution is VGA or above there are errors in the stream. And, the errors increase whenever other DMA interactions occure. For example, if I start the camera transfer and then produce traffic over ethernet the errors increase tremendously. So, my question is: is there a relationship between IDMAC (IPU) and SDMA? And if so, is there a prioritization mechanism in order to raise IDMACs priority? And if not, how could it be explained, that ethernet traffic affects the DMA of the IPU?

Any help would be appreciated.

Thanks in advance.

[Yuri]

Generally WinCE start up code configures system for maximum IPU performance

to avoid display image issues.  Nevertheless, please double check M3IF and AHB

crossbar switch (MAX) settings in the startup.s file.

..\WINCE600\PLATFORM\iMX35-3DS-PDK1_7\SRC\OAL\OALLIB\startup.s

Perhaps it makes sense to play with different settings.

Hope the enclosed i.MX35 block diagram helps to clarify MAX, M3IF configuration.