How are preempted memory accessing by ELCDIF and eDMA?

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How are preempted memory accessing by ELCDIF and eDMA?

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Takashi_Kashiwagi
Senior Contributor I
Hi everyone.
 
I have using IMXRT1050-EVKB with MCUXpresso IDE. And I have a question about preemption eDMA and ELCDIF .

Q. When eDMA (SAI) accesses No-Chache memory on SDRAM while ELCDIF is accessing No-Chache memory on SDRAM, how is each access preempted?
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I understood that eDMA Transfer is preempted by DCHPRIn. But I do not know how eDMA and ELCDIF are preempted.
I found the following phenomenon.
・When you are recording / playing audio with SAI_TransferReceiveEDMA / SAI_TransferSendEDMA while drawing the screen with ELCDIF_SetNextBufferAddr, EDMA transfer does not start occasionally.
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Best Regards.
T.Kashiwagi
4 Replies

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Takashi_Kashiwagi
Senior Contributor I

Hi Vicente Gomez

Thank you for responding.

OK. I'm waiting for your reply.

Best Regards.
T.Kashiwagi

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124 Views
vicentegomez
NXP TechSupport
NXP TechSupport

Hi Sorry for the late response

As for EDMA transfer does not start, does it never start again or just need to wait LCD drawing done to start eDMA?

BTW. The master priority of read/write is determined by NIC module. Customer can configure the masters' priorities with NIC.

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Takashi_Kashiwagi
Senior Contributor I

Hi vicente

Thank you for responding.

As for EDMA transfer does not start, does it never start again or just need to wait LCD drawing done to start eDMA?

Yes, I think so. sorry, Since I have not examined it in detail, I do not understand details.

However, the following phenomenon occurred (Reproducibility is low in either case.).

  • SAI 's eDMA transfer stopped intermittently. (There was periodic noise on the playback sound.)
  • PXP's ROTATE command did not complete

As a result of various experiments, exclusive control to NOCAHCHE memory was done using semaphore etc., it seems that phenomenon does not occur. (But I do not know the real cause).

> BTW. The master priority of read/write is determined by NIC module.

> Customer can configure the masters' priorities with NIC.

Thank you for yout adivse! I'll confirm RM.

Best Regards,

T.Kashiwagi

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124 Views
vicentegomez
NXP TechSupport
NXP TechSupport

Hi

Due the holidays, we have a backlog, we are working to give you an answer , please give us more time.

Regards

Vicente Gomez

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