I2C timeouts reading ublox gps

[yalcinozhabes]

Bug description

I have a Sparkfun SAM-M10Q GPS module which outputs NMEA sentences on i2c port. The output is around 1Kbytes per second. When I read the data to a buffer of size 32 or more bytes, I only get timeouts. When I keep the buffer size 31, it works.

Probably related to #3034 and/or #3167.

To Reproduce

#![no_std]
#![no_main]

use esp_backtrace as _;
use esp_hal::{
    delay::Delay,
    i2c::master::{BusTimeout, Config, I2c},
    main,
};
use esp_println::{print, println};

const DATA_BUF_SIZE: usize = 32;

#[main]
fn main() -> ! {
    let peripherals = esp_hal::init(esp_hal::Config::default());
    let delay = Delay::new();
    let mut i2c = I2c::new(
        peripherals.I2C0,
        Config::default().with_timeout(BusTimeout::Maximum),
    )
    .unwrap()
    .with_sda(peripherals.GPIO16)
    .with_scl(peripherals.GPIO17);

    loop {
        let mut size_buf = [0u8; 2];
        let mut data_buf = [0u8; DATA_BUF_SIZE];
        match i2c.write_read(0x42, &[0xfd], &mut size_buf) {
            Ok(_) => {}
            Err(err) => {
                println!("Error reading the size {:?}", err);
                delay.delay_millis(500);
                continue;
            }
        };
        let size: usize = ((size_buf[0] as u16) << 8 | (size_buf[1] as u16)).into();

        let mut remaining = size;
        println!(
            "Got size_buf {:?}: size:{:?}",
            size_buf, remaining
        );

        while remaining > 0 {
            let bytes_to_read = if remaining > DATA_BUF_SIZE {
                DATA_BUF_SIZE
            } else {
                remaining
            };

            match i2c.write_read(0x42, &[0xff], &mut data_buf[0..bytes_to_read]) {
                Ok(_) => {}
                Err(err) => {
                    println!("Error reading data: {:?}", err);
                    break;
                }
            }
            remaining -= bytes_to_read;
            print!("{}", core::str::from_utf8(&data_buf).unwrap());
        }
        println!("Finished reading GPS data");
        println!("");
        delay.delay_millis(500);
    }
}

For DATA_BUF_SIZE > 31, I just get timeouts.

Got size_buf [0, 0]: size:0
Finished reading GPS data

Got size_buf [5, 8]: size:1288
Error reading data: Timeout
Finished reading GPS data

Got size_buf [9, 239]: size:2543
Error reading data: Timeout
Finished reading GPS data

Got size_buf [19, 222]: size:5086
Error reading data: Timeout
Finished reading GPS data

For DATA_BUF_SIZE=31 everything works as expected.

Expected behavior

Reading into a large buffer should output the same result as a smaller buffer.

Here is the output with the buffer size 31:

Got size_buf [0, 0]: size:0
Finished reading GPS data

Got size_buf [4, 252]: size:1276
$GNRMC,181453.00,A,3406.41996,N,02306.00679,E,0.009,,250225,,,D,V*1F
$GNVTG,,T,,M,0.009,N,0.017,K,D*37
$GNGGA,181453.00,3406.41996,N,02306.00679,E,2,12,0.62,2.3,M,48.4,M,,*4A
$GNGSA,A,3,27,01,14,08,10,02,32,,,,,,1.14,0.62,0.96,1*05
$GNGSA,A,3,68,82,67,83,,,,,,,,,1.14,0.62,0.96,2*03
$GNGSA,A,3,36,09,25,34,04,02,06,11,30,,,,1.14,0.62,0.96,3*03
$GNGSA,A,3,20,30,41,32,,,,,,,,,1.14,0.62,0.96,4*0E
$GNGSA,A,3,,,,,,,,,,,,,1.14,0.62,0.96,5*0A
$GPGSV,3,1,12,01,40,275,32,02,52,291,28,03,14,215,22,08,84,185,37,1*68
$GPGSV,3,2,12,10,41,049,34,14,13,320,23,16,05,177,19,27,48,135,40,1*6E
$GPGSV,3,3,12,32,30,103,30,36,33,142,41,40,19,118,32,49,40,177,31,1*6C
$GPGSV,1,1,01,23,01,042,,0*52
$GLGSV,2,1,06,67,39,050,23,68,49,125,32,73,20,243,18,75,09,340,15,1*74
$GLGSV,2,2,06,82,28,082,31,83,58,036,26,1*71
$GLGSV,1,1,03,69,15,170,,74,27,291,,84,29,302,,0*4D
$GAGSV,3,1,11,02,42,223,30,04,19,055,20,05,07,157,19,06,26,082,29,7*71
$GAGSV,3,2,11,09,26,108,34,10,00,076,08,11,24,070,34,25,09,179,18,7*77
$GAGSV,3,3,11,30,36,295,28,34,44,278,19,36,69,026,33,7*4D
$GAGSV,1,1,01,27,02,332,,0*40
$GBGSV,2,1,06,20,16,187,,30,79,002,,32,55,133,,36,13,245,,0*72
$GBGSV,2,2,06,36,13,245,,41,34,053,,0*71
$GQGSV,1,1,00,0*64
$GNGLL,3406.41996,N,02306.00679,E,181453.00,A,D*77
2316.02679,E,181453.00,A,DFinished reading GPS data

Got size_buf [4, 252]: size:1276
$GNRMC,181454.00,A,3406.41996,N,02306.00688,E,0.114,,250225,,,D,V*1B
$GNVTG,,T,,M,0.114,N,0.211,K,D*3E
$GNGGA,181454.00,3406.41996,N,02306.00688,E,2,12,0.58,2.4,M,48.4,M,,*4D
$GNGSA,A,3,27,01,14,08,10,02,32,,,,,,1.08,0.58,0.92,1*05
$GNGSA,A,3,68,82,67,83,,,,,,,,,1.08,0.58,0.92,2*03
$GNGSA,A,3,36,09,25,34,04,02,06,11,30,,,,1.08,0.58,0.92,3*03
$GNGSA,A,3,20,30,41,32,,,,,,,,,1.08,0.58,0.92,4*0E
$GNGSA,A,3,,,,,,,,,,,,,1.08,0.58,0.92,5*0A
$GPGSV,3,1,12,01,40,275,32,02,52,291,27,03,14,215,22,08,84,185,36,1*66
$GPGSV,3,2,12,10,41,049,41,14,13,320,22,16,05,177,19,27,48,135,41,1*6C
$GPGSV,3,3,12,32,30,103,23,36,33,142,40,40,19,118,31,49,40,177,31,1*6C
$GPGSV,1,1,01,23,01,042,,0*52
$GLGSV,2,1,06,67,39,050,28,68,49,125,31,73,20,243,20,75,09,340,18,1*7A
$GLGSV,2,2,06,82,28,082,31,83,58,036,26,1*71
$GLGSV,1,1,03,69,15,170,,74,27,291,,84,29,302,,0*4D
$GAGSV,3,1,11,02,42,223,29,04,19,055,23,05,07,157,22,06,26,082,31,7*7B
$GAGSV,3,2,11,09,26,108,34,10,00,076,07,11,24,070,35,25,09,179,21,7*73
$GAGSV,3,3,11,30,36,295,28,34,44,278,23,36,69,026,33,7*44
$GAGSV,1,1,01,27,02,332,,0*40
$GBGSV,2,1,06,20,16,187,,30,79,002,,32,55,133,,36,13,245,,0*72
$GBGSV,2,2,06,36,13,245,,41,34,053,,0*71
$GQGSV,1,1,00,0*64
$GNGLL,3406.41996,N,02306.00688,E,181454.00,A,D*7E
2306.00688,E,181454.00,A,DFinished reading GPS data

Got size_buf [0, 0]: size:0
Finished reading GPS data

Environment

• Target device: esp32 (revision v1.0)
• Crate name and version: esp-hal 0.23.1