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SDMA external events not quite working

Question asked by Michal Balcerzak on Sep 8, 2015
Latest reply on Sep 22, 2015 by Michal Balcerzak

How to fire sdma script using SDMA_EXT_EVENT1 line?


i.MX6q reference manual rev.3 revealed us IOMUXC_SDMA_EVENTS14_SELECT_INPUT and IOMUXC_SDMA_EVENTS47_SELECT_INPUT (instead of IOMUXC_SDMA_EVENTS15_SELECT_INPUT) registers. Although not quite clear one can assume sdma event 14 is for ext_line_0 and event 47 (stated as reserved in the manual) is for ext_event_1. Setting GPR0[7] allows to receive sdma external event on DISP0_DAT17 or GPIO_18 pin (or DISP0_DAT16 - it’s not clear since it says it is for SDMA_EVENT[14] which is associated with ext_line_0 elsewhere). Since I can run script fired by event 14 there should be no big problem to use other line to do the same (I need two lines to fire two distinct dma transfers). The problem is I cannot get the same sdma script fired on the other external sdma line connected to pin DISP0_DAT16 (or DISP0_DAT17 if they are switched in the manual).