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iMX6: SDMA external Event 0 not working? (Event 1 does)

Question asked by Rob_iMX6 on Sep 14, 2014
Latest reply on Jul 29, 2018 by 玲 贾

Hi!

 

I'm working on a iMX6DL board with SDMA and external hardware events. There are two external event lines available: Event 0 on pad T21 and Event 1 on pad U24. (and their alternates)

 

Event 1 works as it expected:

     1. set IOMUXC_GPR0[7]=1

     2. set IOMUXC_SW_MUX_CTL_PAD_DISP0_DATA17 to ALT4

     3. set IOMUXC_SDMA_EVENTS15_SELECT_INPUT to DISP0_DATA17 (default anyway)

     4. it is mapped to event 14 of the SDMA. Setting CHNENBL14 to the desired channel (channel 1 in my case), i.e. value 2.

     5. and HO=1, EO=0 and CHNPRI1=7

     -> this will let event 1 trigger my SDMA script nicely.

 

However, the same procedure does not work for the event 0 line. I have verified that the pin is connected (using GPIO) and that the external trigger signal arrives on the chip.

Event 0 is routed to the SDMA by setting IOMUXC_GPR0[0]=1, IOMIXC_SW_MUX_CTL_PAD_DISP0_DATA16=ALT4 and IOMUXC_SDMA_EVENTS14_SELECT_INPUT=DISP0_DATA16

The mapping should be event 2 of the SDMA. I have tried all CHNENBLn, without success.

Furthermore, I have enabled all clocks to be sure (CCM_CCGRn=0xfffffff), without success either.

 

Any ideas? Looks like a chip bug to me...

 

Regards,

-Urs

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