Recent updates appear to cause SPI communication lockup

[ryan-summers]

In booster, using the latest master causes our application to lock up and encounter watchdog resets. Backtraces consistently have pointed to some of the SPI functions as the root cause, and using older revisions of the f4xx-hal do not have these issues.

Below is the backtrace when I Ctrl+C during a lockup of our idle() task.

   0: stm32f4xx_hal::spi::Inner<SPI>::check_read
        at C:\Users\rsummers\.cargo\git\checkouts\stm32f4xx-hal-fe8350cc04cacf3f\4144b1d\src\spi.rs:764:16
   1: stm32f4xx_hal::spi::Spi<SPI,_,W>::read_nonblocking
        at C:\Users\rsummers\.cargo\git\checkouts\stm32f4xx-hal-fe8350cc04cacf3f\4144b1d\src\spi.rs:932:9
   2: stm32f4xx_hal::spi::Spi<SPI,_,W>::transfer_in_place
        at C:\Users\rsummers\.cargo\git\checkouts\stm32f4xx-hal-fe8350cc04cacf3f\4144b1d\src\spi.rs:945:32
   3: stm32f4xx_hal::spi::hal_02::blocking::<impl embedded_hal::blocking::spi::Transfer<u8> for stm32f4xx_hal::spi::Spi<SPI>>::transfer
        at C:\Users\rsummers\.cargo\git\checkouts\stm32f4xx-hal-fe8350cc04cacf3f\4144b1d\src\spi\hal_02.rs:61:13
   4: <w5500::bus::four_wire::FourWire<Spi,ChipSelect> as w5500::bus::Bus>::read_frame::{{closure}}
        at C:\Users\rsummers\.cargo\registry\src\index.crates.io-6f17d22bba15001f\w5500-0.4.1\src\bus\four_wire.rs:40:13
   5: <w5500::bus::four_wire::FourWire<Spi,ChipSelect> as w5500::bus::Bus>::read_frame
        at C:\Users\rsummers\.cargo\registry\src\index.crates.io-6f17d22bba15001f\w5500-0.4.1\src\bus\four_wire.rs:35:22
   6: w5500::socket::Socket::get_receive_size
        at C:\Users\rsummers\.cargo\registry\src\index.crates.io-6f17d22bba15001f\w5500-0.4.1\src\socket.rs:186:13
   7: w5500::raw_device::RawDevice<SpiBus>::read_frame
   8: booster::hardware::external_mac::<impl smoltcp::phy::Device for booster::hardware::Mac>::receive

If I revert to 2d8d882, this issue goes away. I'm not sure what's changed since then

[burrbull]

Possibly something in #673
Try 4c16f3d, please.

[ryan-summers]

Hmm. There's something else going on, as master now appears to work just fine. This is likely something related to hardware or register configurations, sorry for the false-positive here. If I keep seeing oddness, I'll reopen.

[ryan-summers]

Ah intriguing. The issue appears to be caused by a difference between Release and Debug configurations. Debug is working fine, but Release is not.

I have returned with some more testing results:

• Using our current main branch (in booster), I can confirm that both Release and Debug runs complete normally. This uses 2d8d882
• Updating our main branch to use stm32-rs/master makes the Release build then fail to execute.

I retried 4c16f3d with our main branch and confirmed that this appears to be the first commit where this defect appears

[burrbull]

Try https://github.com/stm32-rs/stm32f4xx-hal/tree/spi_revert. It reverts check_read & check_send.

[ryan-summers]

Interestingly, that branch indeed seems to be working without issue

[burrbull]

Interestingly, that branch indeed seems to be working without issue

Yeah, strange.
I've added asserts in that branch. Could you check does it fault on any assert?

[ryan-summers]

Even more strangely - the commit with the asserts does not work, but the commit immediately before does. Perhaps this is a race condition of some sort that arises because of extra processing time required by the new API, although I have not profiled things on my side extensively (I'm just looking at very high-level functionality of the app, i.e. it connects over MQTT or does not)

[ryan-summers]

I might have time to dig deeper later on this, but I need to head home for the day now

[burrbull]

@ryan-summers Try #709, please.

[ryan-summers]

Still not working on my end, it seems to keep hitting lockup in the following functions:

stack backtrace:
   0: stm32f4xx_hal::spi::Inner<SPI>::check_read
        at C:\Users\rsummers\.cargo\git\checkouts\stm32f4xx-hal-fe8350cc04cacf3f\26f646d\src\spi.rs:766:19
   1: stm32f4xx_hal::spi::Spi<SPI,_,W>::read_nonblocking
        at C:\Users\rsummers\.cargo\git\checkouts\stm32f4xx-hal-fe8350cc04cacf3f\26f646d\src\spi.rs:933:9
   2: stm32f4xx_hal::spi::Spi<SPI,_,W>::transfer_in_place
        at C:\Users\rsummers\.cargo\git\checkouts\stm32f4xx-hal-fe8350cc04cacf3f\26f646d\src\spi.rs:946:32
   3: stm32f4xx_hal::spi::hal_02::blocking::<impl embedded_hal::blocking::spi::Transfer<u8> for stm32f4xx_hal::spi::Spi<SPI>>::transfer
        at C:\Users\rsummers\.cargo\git\checkouts\stm32f4xx-hal-fe8350cc04cacf3f\26f646d\src\spi\hal_02.rs:61:13
   4: <w5500::bus::four_wire::FourWire<Spi,ChipSelect> as w5500::bus::Bus>::read_frame::{{closure}}

[burrbull]

It is strange. I was sure spi_revert and flags-test2 produce same code. 8 byte different

[burrbull]

I've merged revert commits.