TDA4VM: [i2096]: UART: Spurious UART Interrupts When Using DMA

Nazim Haque

Part Number: TDA4VM
Other Parts Discussed in Thread: TDA4VH

Hello,

Could you please support me on below errata.

------------------Errata text-------------------------

[i2096]: UART: Spurious UART Interrupts When Using DMA
Failure:
Spurious UART interrupts may occur when DMA mode (UART_FCR[3] DMA_MODE) is enabled and DMA is used to read data from RX FIFO. The Interrupt Controller flags that a UART interrupt has occurred; however, the associated UART_IIR_UART[0] IT_PENDING
bit remains set to 1, indicating that no interrupt is pending.

Workaround:
Acknowledge the spurious interrupts for every occurrence. The issue can be avoided by disabling Receive Data Interrupt (RDI) using the UART_IER_UART[0] RHR_IT bit; however, be aware that this also disables RX timeout interrupts, which may not be practical for all use cases.

----------------------------------------------------------

Question:

I am not using UART_FCR[3] DMA_MODE bit to enable DMA in my driver. I am using UART_SCR[2-1] DMA_MODE_2 = 1 and UART_SCR[0].DMA_MODE_CTL = 1 for transmitting and receiving data. Is the errata i2096 applicable for this configuration as well?

Thanks

Nazim

over 2 years ago

0 Diwakar Dhyani over 2 years ago

TI__Guru 60565 points

Hi Nazim

Thanks for reaching out !

Thread is assigned to the respective owner, will try to respond within a week.

Regards
Diwakar

0 Keerthy J over 2 years ago in reply to Diwakar Dhyani

TI__Guru**** 166450 points

Nazim,

Can you confirm which OS you are using?

Linux or RTOS? Are you writing your own driver?

Best Regards,

Keerthy

0 Nazim Haque over 2 years ago in reply to Keerthy J

Prodigy 110 points

Hi Keerthy,

Its own UART driver. There is no OS running.

Thanks

Nazim

0 Keerthy J over 2 years ago in reply to Nazim Haque

TI__Guru**** 166450 points

Hi Nazim,

Checking internally I will respond once I have feedback on this.

Best Regards,

Keerthy

0 Keerthy J over 2 years ago in reply to Keerthy J

TI__Guru**** 166450 points

Hello Nazim,

Our hardware experts will respond to this. Thanks for your patience.

Best Regards,
Keerthy

0 Nazim Haque over 2 years ago in reply to Keerthy J

Prodigy 110 points

Hello Keerthy,

Any updates?

Thanks

0 Suman Anna over 2 years ago in reply to Nazim Haque

TI__Guru** 116625 points

Hi Nazim,

I understand that you are using TDA4VM for your development, but is this really the end target device?

The i2096 Errata is not applicable to TDA4VH SoCs, which may be your final target device.

regards

Suman

0 Nazim Haque over 2 years ago in reply to Suman Anna

Prodigy 110 points

Hi Suman,

The UART driver shall run in TDA4VM,TDA4VH and TDA4VE SoCs. I just wanted to make sure setting DMA mode using SCR register is affected by errata or not.

Thanks

Nazim

0 Suman Anna over 2 years ago in reply to Nazim Haque

TI__Guru** 116625 points

Hi Nazim,

Nazim Haque said:
The UART driver shall run in TDA4VM,TDA4VH and TDA4VE SoCs

If the errata is valid, then I hope you AutoSAR code will have a configuration flag to enable this or disable this depending on the SoC.

Nazim Haque said:
I just wanted to make sure setting DMA mode using SCR register is affected by errata or not.

The errata text doesn't say anything about the DMA mode using SCR, and is explicit in calling out the DMA mode using FCR. I would imply then that this errata would not be applicable for your usecase.

regards

Suman

+1 Nazim Haque over 2 years ago in reply to Suman Anna

Prodigy 110 points

Hi Suman,

Thanks for the confirmation.

Nazim

0 B.C. over 2 years ago in reply to Nazim Haque

TI__Genius 17116 points

Nazim, actually we are still confirming if DMA mode using SCR is affected.

0 B.C. over 2 years ago in reply to B.C.

TI__Genius 17116 points

Our design team has confirmed that the errata applies to all DMA modes (set by either FCR or SCR). We will update the errata to clarify this.

0 Nazim Haque over 2 years ago in reply to B.C.

Prodigy 110 points

Could you please provide the updated errata.

0 B.C. over 2 years ago in reply to Nazim Haque

TI__Genius 17116 points

Here is the updated Description that will appear in the next errata document release:

"Spurious UART interrupts may occur when DMA mode is enabled (via either FCR.DMA_MODE or SCR.DMA_MODE_2, selectable by SCR.DMA_MODE_CTL) and DMA is used to read data from RX FIFO. The Interrupt Controller flags that a UART interrupt has occurred; however, the associated IT_PENDING bit remains set to 1, indicating that no interrupt is pending."

0 Nazim Haque over 2 years ago in reply to B.C.

Prodigy 110 points

Will there be new errata revision for the above change in statement? And when I can expect the revised errata?

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TDA4VM: [i2096]: UART: Spurious UART Interrupts When Using DMA