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machine: [rp2] discount scheduling delays in I2C timeouts #4876

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merged 1 commit into from
May 7, 2025
Merged

machine: [rp2] discount scheduling delays in I2C timeouts #4876

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20 changes: 13 additions & 7 deletions src/machine/machine_rp2_i2c.go
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Original file line number Diff line number Diff line change
Expand Up @@ -86,10 +86,7 @@ func (i2c *I2C) Tx(addr uint16, w, r []byte) error {
if i2c.mode != I2CModeController {
return ErrI2CWrongMode
}

// timeout in microseconds.
const timeout = 40 * 1000 // 40ms is a reasonable time for a real-time system.
return i2c.tx(uint8(addr), w, r, timeout)
return i2c.tx(uint8(addr), w, r)
}

// Listen starts listening for I2C requests sent to specified address
Expand Down Expand Up @@ -218,8 +215,8 @@ func (i2c *I2C) enable() {
//
//go:inline
func (i2c *I2C) disable() error {
const MAX_T_POLL_COUNT = 64 // 64 us timeout corresponds to around 1000kb/s i2c transfer rate.
deadline := ticks() + MAX_T_POLL_COUNT
const timeout_us = 4_000
deadline := ticks() + timeout_us
i2c.Bus.IC_ENABLE.Set(0)
for i2c.Bus.IC_ENABLE_STATUS.Get()&1 != 0 {
if ticks() > deadline {
Expand Down Expand Up @@ -285,7 +282,8 @@ func (i2c *I2C) deinit() (resetVal uint32) {
}

// tx performs blocking write followed by read to I2C bus.
func (i2c *I2C) tx(addr uint8, tx, rx []byte, timeout_us uint64) (err error) {
func (i2c *I2C) tx(addr uint8, tx, rx []byte) (err error) {
const timeout_us = 4_000
deadline := ticks() + timeout_us
if addr >= 0x80 || isReservedI2CAddr(addr) {
return ErrInvalidTgtAddr
Expand Down Expand Up @@ -338,7 +336,9 @@ func (i2c *I2C) tx(addr uint8, tx, rx []byte, timeout_us uint64) (err error) {
return errI2CWriteTimeout // If there was a timeout, don't attempt to do anything else.
}

before := ticks()
gosched()
deadline += ticks() - before
}

abortReason = i2c.getAbortReason()
Expand All @@ -361,7 +361,9 @@ func (i2c *I2C) tx(addr uint8, tx, rx []byte, timeout_us uint64) (err error) {
return errI2CWriteTimeout
}

before := ticks()
gosched()
deadline += ticks() - before
}
i2c.Bus.IC_CLR_STOP_DET.Get()
}
Expand All @@ -382,7 +384,9 @@ func (i2c *I2C) tx(addr uint8, tx, rx []byte, timeout_us uint64) (err error) {
first := rxCtr == 0
last := rxCtr == rxlen-1
for i2c.writeAvailable() == 0 {
before := ticks()
gosched()
deadline += ticks() - before
}
i2c.Bus.IC_DATA_CMD.Set(
boolToBit(first && rxStart)<<rp.I2C0_IC_DATA_CMD_RESTART_Pos |
Expand All @@ -399,7 +403,9 @@ func (i2c *I2C) tx(addr uint8, tx, rx []byte, timeout_us uint64) (err error) {
return errI2CReadTimeout // If there was a timeout, don't attempt to do anything else.
}

before := ticks()
gosched()
deadline += ticks() - before
}
if abort {
break
Expand Down