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fix: LpUart::new() set tx_idle_num to 0 twice #2860

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zpg6
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@zpg6 zpg6 commented Dec 21, 2024

Thank you for your contribution!

We appreciate the time and effort you've put into this pull request.
To help us review it efficiently, please ensure you've gone through the following checklist:

Submission Checklist 📝

  • I have updated existing examples or added new ones (if applicable).
  • I have used cargo xtask fmt-packages command to ensure that all changed code is formatted correctly.
  • My changes were added to the CHANGELOG.md in the proper section.
  • I have added necessary changes to user code to the Migration Guide.
  • My changes are in accordance to the esp-rs API guidelines

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Pull Request Details 📖

Description

In the LpUart::new() function in esp-hal/src/uart.rs

// 🟨 FIRST TIME:
// Set tx idle
me.uart
    .idle_conf()
    .modify(|_, w| unsafe { w.tx_idle_num().bits(0) });

// Disable hw-flow control
me.uart
    .hwfc_conf()
    .modify(|_, w| w.rx_flow_en().clear_bit());

// Get source clock frequency
// default == SOC_MOD_CLK_RTC_FAST == 2

// LP_CLKRST.lpperi.lp_uart_clk_sel = 0;
unsafe { LP_CLKRST::steal() }
    .lpperi()
    .modify(|_, w| w.lp_uart_clk_sel().clear_bit());

// Override protocol parameters from the configuration
// uart_hal_set_baudrate(&hal, cfg->uart_proto_cfg.baud_rate, sclk_freq);
me.change_baud_internal(config.baudrate, config.clock_source);
// uart_hal_set_parity(&hal, cfg->uart_proto_cfg.parity);
me.change_parity(config.parity);
// uart_hal_set_data_bit_num(&hal, cfg->uart_proto_cfg.data_bits);
me.change_data_bits(config.data_bits);
// uart_hal_set_stop_bits(&hal, cfg->uart_proto_cfg.stop_bits);
me.change_stop_bits(config.stop_bits);

// 🟨 SECOND TIME:
// uart_hal_set_tx_idle_num(&hal, LP_UART_TX_IDLE_NUM_DEFAULT);
me.change_tx_idle(0); // LP_UART_TX_IDLE_NUM_DEFAULT == 0

I removed 🟨 FIRST TIME, as I do not see any impacts of leaving tx_idle_num as default (256) until it is called a few lines later.

Testing

Ongoing

@zpg6
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zpg6 commented Dec 29, 2024

Can someone more familiar with LpUart take a look at this? Need some help to regression test it and confirm it's truly redundant, just recognized it when working on a similar PR #2859 for the same setting to the main Uart.

@bjoernQ
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bjoernQ commented Dec 30, 2024

While sometimes something like that might have a (wanted) side-effect it doesn't seem so in this case and is probably just an oversight.

We currently don't have hil-tests for lp-uart and setting it up would probably require some re-wiring in the test-setup - so manual verification is good enough

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2 participants