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musb with EZBRD in full DMA (from kernel 3.7 on)

Question asked by Rob. on Jul 30, 2013
Latest reply on Jul 25, 2014 by ScottJiang

Using musb with BF526-devices and approx. 20 Mbps throughput (iperf testing, USB-wifi stick), a musb-hdrc interrupt yields a rate of approx. 8 kHz. This significantly deteriorates application performance (e.g. sound, video processing).

 

I found that from kernel 3.7 on a true DMA support is included with musb. So I went to get things working. To summarize: with 3.7 I got a correct build process, but the musb driver isn't loaded. 3.8 yields some build problems, but 3.9 and 3.10 are OK again. Here the driver is anyhow loaded, but the following report is given from the boot proces:

 

musb-hdrc musb-hdrc.0.auto: musb_init_controller failed with status -517

platform musb-hdrc.0.auto: Driver musb-hdrc requests probe deferral

 

I guess that the problem is in some necesary board file updates (Analog Devices EZBRD BF526). git shows that latest update is related to kernel 3.5.

 

I'd highly appreciate some quick help, in order to be able to start tests with musb DMA resources as soon as possible.

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