What does DMA transaction error really mean

Philip Balister

I have a driver that is using DMA to copy data to/from an FPGA attached to the GPMC controller of a 3530. Once in a while, I see the following message in from the Linux (2.6.35) kernel: "DMA transaction error with device 0". Reading the TRM suggests this means one of the endpoints reported an error. The two endpoint here are the system ram and the gpmc controller. Given this works most of the time, any thoughts on what could cause this?

I can provoke the problem by driving the transfers hard and clicking on windows in X.

Thanks,

Philip

over 14 years ago

0 Rama Sai Krishna vakkantula over 14 years ago

Prodigy 10 points

Hi Philip,

I am trying to read data from the PNAND device connected to OMAP 3530 using the DMA. But I am also getting the following message "DMA transaction error with device 0".

I could not understand what exactly is causing this error. Could you please share some information on what could be causing this kind of error and how to resolve, if you have already found a solution to your problem.

Thanks,

krishna.

0 Philip Balister over 14 years ago in reply to Rama Sai Krishna vakkantula

Prodigy 50 points

FWIW , the DMA transaction error seems to have gone away after I emabled bursting in the dma control regs. Which is a bit odd, sonce it looks like I didn't change from the gpmc address being fixed, to letting it increment.

0 Midson over 14 years ago in reply to Philip Balister

Intellectual 835 points

1. How did you enabled the DMA Bursting? 2. Are you referring the OMAP_DMA_AMODE_CONSTANT in DMA Dest parameter? omap_set_dma_dest_params(info->dma_ch, 0, OMAP_DMA_AMODE_CONSTANT, info->phys_base, 0, 0);

0 Philip Balister over 14 years ago in reply to Philip Balister

Prodigy 50 points

The DMA Transaction error ordeal continues, after adjusting the GPMC cycle settings, the DMA Transaction error is back.

Does anyone have any insight into what this means?

DOUBLE RAINBOW, WHAT DOES IT MEAN?

Philip

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What does DMA transaction error really mean