imx8mp UART breaks if DMA is enabled

[bofh]

Hello,

We are trying to configure UARTs 1 and 4 (serial@30860000 and serial@30a60000) on an imx8mp based board running i.MX Linux 5.15.71 (lf-5.15.y), but they appear to be failing unless we disable DMA by deleting the "dmas" and "dma-names" properties in the device tree.

With DMA enabled, when trying to transmit data over any of the UARTs the following errors are shown:

[ 552.364843] imx-sdma 30bd0000.dma-controller: All bds consumed,restart now.
[ 564.763063] imx-sdma 30bd0000.dma-controller: All bds consumed,restart now.

No data is actually transmitted, and further attempts to use the UARTs or alter their settings may hang indefinitely.

We verified that the imx-sdma firmware is being loaded correctly, and no other errors related to the DMA controllers are reported.

Do you have any suggestion?

[ericnelsonaz]

FWIW, there's a fix for a BD leak in the 6.1 kernel tree.

[Bio_TICFSL]

Hello,

You might check if other module use dma as i2C, etc you remove but at the compile time the other peripheral need it.

Regards