[MCXA] dma: Peripheral Paced Scatter-Gather - #6686
Open
ayodejiige wants to merge 5 commits into
Open
Conversation
|
This pull request is a draft, so it isn't in the review queue yet. Mark it as ready for review when you'd like someone to look at it. |
ayodejiige
marked this pull request as ready for review
August 2, 2026 00:08
felipebalbi
requested changes
Aug 3, 2026
Comment on lines
+105
to
+122
| // Run TX gather and RX scatter concurrently. | ||
| let rx_fut = async { | ||
| defmt::info!("RX: scatter chain armed"); | ||
| let t = rx_sg.build_borrowed(&mut rx_ch).unwrap(); | ||
| let res = t.await; | ||
| defmt::info!("RX: transfer done, result ok={}", res.is_ok()); | ||
| res | ||
| }; | ||
|
|
||
| let tx_fut = async { | ||
| defmt::info!("TX: gather chain starting"); | ||
| let t = tx_sg.build_borrowed(&mut tx_ch).unwrap(); | ||
| let res = t.await; | ||
| defmt::info!("TX: transfer done, result ok={}", res.is_ok()); | ||
| res | ||
| }; | ||
|
|
||
| let (rx_res, tx_res) = join(rx_fut, tx_fut).await; |
Contributor
There was a problem hiding this comment.
Run something like this in a loop. We need to know that this API remains robust even after running for many days.
Comment on lines
+73
to
+103
| // Build both scatter-gather chains. | ||
| let mut rx_sg = ScatterGatherBuilder::<u8, PeripheralPaced>::new(); | ||
| rx_sg | ||
| .add_transfer_segment(PeripheralSegment::peripheral_to_memory(data_rx, &mut rx1)) | ||
| .unwrap() | ||
| .add_transfer_segment(PeripheralSegment::peripheral_to_memory(data_rx, &mut rx2)) | ||
| .unwrap() | ||
| .add_transfer_segment(PeripheralSegment::peripheral_to_memory(data_rx, &mut rx3)) | ||
| .unwrap(); | ||
|
|
||
| let mut tx_sg = ScatterGatherBuilder::<u8, PeripheralPaced>::new(); | ||
| tx_sg | ||
| .add_transfer_segment(PeripheralSegment::memory_to_peripheral(&PAYLOAD1, data_tx)) | ||
| .unwrap() | ||
| .add_transfer_segment(PeripheralSegment::memory_to_peripheral(&PAYLOAD2, data_tx)) | ||
| .unwrap() | ||
| .add_transfer_segment(PeripheralSegment::memory_to_peripheral(&PAYLOAD3, data_tx)) | ||
| .unwrap(); | ||
|
|
||
| defmt::info!( | ||
| "TX chain: {} segments, RX chain: {} segments", | ||
| tx_sg.segment_count(), | ||
| rx_sg.segment_count() | ||
| ); | ||
|
|
||
| // Enable LPUART2 DMA request lines directly via PAC — the HAL does not | ||
| // yet provide a method for this on `Lpuart`. This is only used for the purpose of this example. | ||
| hal::pac::LPUART2.baud().modify(|w| { | ||
| w.set_tdmae(true); | ||
| w.set_rdmae(true); | ||
| }); |
Contributor
There was a problem hiding this comment.
I don't think this will survive for long if we put all the onus on the users. How about an API where the user passes a slice of slices and the driver ensures safe use of the DMA block?
Author
There was a problem hiding this comment.
I was following the existing ScatterGather pattern but with peripheral paced transfers enabled. Is what you are suggesting akin to having something like read_from_peripheral_scatter and write_to_peripheral_gather as methods under DmaChannel which takes in slices?
felipebalbi
changed the title
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Extend the
ScatterGatherBuilderDMA API to support peripheral paced mode, alongside aLPUART2loopback example that exercises it.