Statemachine improvements #6360
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This can be used to make sure a PIO has actually finished all data it was schedule to receive via a 'once' background_write
Always use DMA if swap flag is enabled. Improve docs a bit
Works in conjunction with adafruit/circuitpython#6360 * get rid of the need for 'filler' in morse demo * make neopixels work super fast without explicit byteswapping
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I fixed a doc formatting issue (extra """). I added (reverse) in the documentation for the swap arguments, to clarify that the byte order is reversed, since swap is not so obvious for the 4-byte case. If you disagree with that, we can change it back. I will not merge pending your thoughts on that.
| @@ -674,13 +674,26 @@ static bool _transfer(rp2pio_statemachine_obj_t *self, | |||
| size_t len = MAX(out_len, in_len); | |||
| bool tx = data_out != NULL; | |||
| bool rx = data_in != NULL; | |||
| if (len >= dma_min_size_threshold) { | |||
| bool use_dma = len >= dma_min_size_threshold || swap_out || swap_in; | |||
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Is there any risk that having DMAs for sizes less then the threshold that require swaps will cause either a speed issue for the small DMAs or potential exhaustion of DMAs? It may not be any concern just wanted to bring it up.
Rest looks great.
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I don't really know. :) There are 12 DMAs; audio might claim 2 in the background, and this code now claims up to 2. so it looks like there should be plenty left over.
At first I wanted to say this was no change for existing code, but it IS a change. Before, if you had a LARGE buffer but couldn't allocate DMA, the code would fall back to copying in a CPU loop. Now, it will return an error.
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@dhalbert thanks, the doc changes look fine to this human but I see the doc build is (still) failing. |
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Now if only I knew how to write the core code to allow 'await state_machine.async_write(buf)` |
For this, I think the easiest thing to do is to pass an |
This makes it possible to
Closes: #6359, closes #6357