How to change priority of dma controller RT1020

[hanmant]

Hi,

I'm using Rt1020 processor.

I want make high priority uart dma than than the cpu .

And also make the uart than Spi dma or cmsis interrupt 

Also in uart dma want make Rx priority high.

I

Can you please give me suggestions 

[EdwinHz]

Hi @hanmant,

You can change the priority of each eDMA channel by setting its respective DCHPRIn register. The priorities go from the lowest one of '0' to the highest one of '15'. I believe what you are looking for is to set the DCHPRI register of your UART channel to the highest possible value of 15. For more information, please look at Section "6.5.5.18 Channel Priority (DCHPRI0 - DCHPRI31)" of the RT1020RM.

BR,
Edwin.

[hanmant]

Hi @Edwin,

Thanks for reply .
I want give more priority to DMA controller over CPU .
Can you tell me the API's to set it.

[hanmant]

Also how to change the priority of Uart DMA over SPI

[EdwinHz]

Hi @hanmant,

I'm afraid that the DMA cannot have a higher priority than the CPU itself.

If you wish to better manage the priorities between peripherals, I highly suggest you use FreeRTOS instead of BareMetal. In BareMetal, all you can achieve is what I previously shared with you about the DMA priorities; there is no way of changing peripheral priorities.

With FreeRTOS, you can set priorities for each task, and with a task for each peripheral, you can set priorities for each peripheral.

Please look into the FreeRTOS example codes we provide on the RT1020 SDK for more information on how to set task priorities.

BR,
Edwin.

[hanmant]

Hi @Edwin,
Can we using this api at least for dma ,
// Set DMA channel preemption configuration
preemptionConfig.enableChannelPreemption = true;
preemptionConfig.enablePreemptAbility = true;
preemptionConfig.channelPriority = 14; // Set priority to 14 for TX channel
EDMA_SetChannelPreemptionConfig(EXAMPLE_LPUART_DMA_BASEADDR, LPUART_TX_DMA_CHANNEL, &preemptionConfig);

preemptionConfig.channelPriority = 15; // Set priority to 15 for RX channel
EDMA_SetChannelPreemptionConfig(EXAMPLE_LPUART_DMA_BASEADDR, LPUART_RX_DMA_CHANNEL, &preemptionConfig);

Please confirm.

[EdwinHz]

Hi @hanmant,

Yes, it looks good.

BR,
Edwin. 

[hanmant]

Hi @Edwin
This piece of code is not working ,means when i add this lines code in my code then whole application got stuck
const edma_channel_Preemption_config_t Channel_preemption_config = {
.enableChannelPreemption = false,
.enablePreemptAbility = true,
.channelPriority = 15U
};
const edma_channel_Preemption_config_t Channel14_preemption_config = {
.enableChannelPreemption = false,
.enablePreemptAbility = true,
.channelPriority = 14U
};

EDMA_SetChannelPreemptionConfig(EXAMPLE_LPUART_DMA_BASEADDR,LPUART_TX_DMA_CHANNEL, &Channel_preemption_config);
EDMA_SetChannelPreemptionConfig(EXAMPLE_LPUART_DMA_BASEADDR, LPUART_RX_DMA_CHANNEL, &Channel14_preemption_config);

Note: with this uart DMA there is another i2c DMA also there but i have not set priority of i2c DMA

[EdwinHz]

Hi @hanmant,

Could you be more specific? Where does the application get stuck? Do you receive a hardfault, or what kind of error do you get?

BR,
Edwin. 

[hanmant]

Hi @Edwin,

This is stuck into the i2c DMA.
but when i remove the priority related code then it works fine.
Is there priority conflict happening here? if so , then how resolve this?

[EdwinHz]

Hi @hanmant,

That seems to be the case. Is there a reason why you require this priority related code if the application works fine without it? Why not keep the code without this part if it works OK? 

[hanmant]

Hi @Edwin,
My uart dma communication is running at 3Mb baud rate .
So currently I'm facing problem of packets dropping.
So I want to set high priority for Uart Dma than other dma like spi ,i2c.

[EdwinHz]

Hi @hanmant,

As I previously mentioned, you can change the DMA's priority for each channel by using the DCHPRIn register. Have you tried using this to set up a higher priority for UART than the rest of the DMA channels?

BR,
Edwin.

[hanmant]

Hi @EdwinHz,

I'm not setting priority to another peripheral like I2C ,SPI.
Only i trying to set priority to Uart DMA channel by using the DCHPRIn register . But still my code is got stuck in I2C dma .
Is there anything is conflicting I2C Dma if Yes then How to check that and How to disable to priority of others DMA channels.

[hanmant]

Hi @EdwinHz 

I'm still waiting for my answer.

  Can you please tell how you tried at your end by taking I2C and Uart DMA and setting the priority to UART dma channel as High using the DCHPRIn registers.

Please give me example code.

[EdwinHz]

Hi @hanmant,

Please take a look at the "evkmimxrt1020_lpuart_edma_transfer" example code from the RT1020 SDK for aid on how to setup the dma + uart connection. 

BR,
Edwin.

[hanmant]

@EdwinHz 

Your not responding to my question since long time.

[hanmant]

Hi @EdwinHz,

waiting for your response.