We were using OSPI in indirect mode via DMA and noticed that the transfer future would never resolve. It was forever busy-looping in `finish_dma()` on the `while !regs.sr().read().tcf() {}` line.
After some debugging we noticed that the the `TEF` flag is set. The data sheet says the following about this flag:
> The following errors set the TEF flag in OCTOSPI_SR and generates an interrupt if enabled (TEIE = 1 in OCTOSPI_CR):
> - in indirect or automatic status-polling mode, when a wrong address has been programmed in OCTOSPI_AR (according to the device size defined by DEVSIZE[4:0]).
> - in indirect mode, if the address plus the data length exceed the device size: TEF is set as soon as the access is triggered.
Indeed we were configuring our device size to 0 while specifying a non-zero address.
Detect this condition and return an error early - as soon as we configure the registers (which, according to the data sheet, should be enough to raise the flag)
Also document this behavior on the respective TransferConfig and Config fields.
Testing
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See https://github.com/goodhoko/spi-error-test/blob/main/src/main.rs
- Make DQSE / SIOO configurable
- Make write instruction configurable
- Fix bug where the address DTR was using the config for the instruction DTR instead of its own
- Configure DQS pin
Since the register structs are no-field structs with
`repr(transparent)`, we can use them in the LinearItem with `repr(C)`.
This allows the user to call the convenient named setter functions for
the registers instead of manually changing the bits of the u32.
- It is now possible to pass a linked-list table to the ring-buffer with
the `new_with_table()` function or use the `new()` function for a basic
ring-buffer setup.
- A `simple_ring_buffer_table()` function was added to the read and
write ring-buffers to generate the same table as the one created by
`new()` in case the user only wants to customize the default table
options.
- RegisterUpdaters have been removed as the user now has direct access
to the table and its items if needed.
See: https://github.com/elagil/embassy/pull/1#issuecomment-2891997294
See
https://github.com/embassy-rs/embassy/pull/3923#issuecomment-2888810087
The default configuration of the channel which was done in `start()` is
now done in `new()` this allows overriding some settings through the new
`get_dma_channel` function. Only ringbuffers support this;
`LinkedListTransfer` and `Transfer` do not support that yet.
