topic Re: Vybrid DMA inter-core collisions in Vybrid Processors

Vybrid DMA inter-core collisions

kubiznak_petr — Mon, 10 Mar 2014 06:52:28 GMT

Two months ago, I described a DMA collision issue with Vybrid audio when a playback is started on Linux (A5) while MQX is running on M4 (Vybrid audio (sgtl5000)).

Now I am experiencing a mirror problem - when an SPI DMA operation starts on M4, Linux immediately dies. Is there any document describing which DMA channels are used by Timesys Linux so I can setup MQX to use different channels and avoid the issues? Can that be easily seen/modified in the Linux sources?

Re: Vybrid DMA inter-core collisions

karina_valencia — Mon, 10 Mar 2014 19:17:03 GMT

timesyssupport can you attend this case?

Re: Vybrid DMA inter-core collisions

timesyssupport — Mon, 10 Mar 2014 20:33:23 GMT

Hello Petr,

On the Vybrid Tower board, Linux uses the following DMA channels on DMA engine 0, mux 0:

UART1 RX - Channel 4
UART1 TX - Channel 5

DSPI0 RX - Channel 12

DSPI0 TX - Channel 13

SAI2 (I2S2) RX - Channel 20
SAI2 (I2S2) TX - Channel 21

A list of all DMA channels can be found in the Linux source tree, at arch/arm/plat-mxc/include/mach/mvf_edma.h

Thanks, and let me know if you have any questions.

Timesys Support

Re: Vybrid DMA inter-core collisions

kubiznak_petr — Tue, 11 Mar 2014 17:19:07 GMT

Good, that should help, thank you.

Re: Vybrid DMA inter-core collisions

carlovalgocela — Wed, 10 Jun 2015 00:48:21 GMT

Hello timesyssupport

i would like to ask how in Linux the peripherals are assigned to DMA channels on DMA engine 0, mux 0?

Re: Vybrid DMA inter-core collisions

timesyssupport — Thu, 11 Jun 2015 15:43:36 GMT

Hello carlovalgocela

The following link should be helpful:

https://linuxlink.timesys.com/docs/wiki/engineering/bsp_userguide_twr-vf65gs10#DMA

Thank you,

Timesys Support