Summary

STM32 UART driver behavior change

Review Request #5 — Created Jan. 2, 2023 and updated Jan. 2, 2023, 12:38 p.m.

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Giovanni

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ChibiOS

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/trunk

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Description

UART driver behavior change, this is the original proposal:

https://forum.chibios.org/viewtopic.php?f=38&t=6171

I have not fully understood the request but my concern is that only USART1 has RTS/CTS capability.

Testing Done

Description:: UART driver behavior change, this is the original proposal:

https://forum.chibios.org/viewtopic.php?f=38&t=6171

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I have not fully understood the request but my concern is only USART1 has RTS/CTS capability.
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I have not fully understood the request but my concern is that only USART1 has RTS/CTS capability.

Logic looks reversed for char CB to enable DMA. Should be uartp->config->rxchar_cb != NULL)

Giovanni Jan. 2, 2023, 10:54 a.m.

Why the complex check? wouldn't

((uartp->usart->CR3 & USART_CR3_RTSE_Msk) != 0)

be sufficient? do not enable DMA if RTS is enabled.

Note that the DMA is enabled there in order to prevent overflows, the idea is that you restart a read quickly enough before data is read by the DMA and lost. I am not sure that the patch is appropriate (but I never seriously used the UART driver).

mringwal Jan. 2, 2023, 12:36 p.m.

Correct, the logic was wrong. I've upaded a new patch that uses "byte callback set OR RTS not enabled".

Wouldn't something like this easier?

static void uart_enter_rx_idle_loop(UARTDriver *uartp) {

  if ((uartp->usart->CR3 & USART_CR3_RTSE_Msk) == 0) {
    /* All the OLD code here.*/
  }
}


The new condition could also be make optional in order to retain the previous behavior.

mringwal Jan. 2, 2023, 12:38 p.m.

Complex logic: I've tried to make the smallest change to fix my need. The overall goal is to not loose bytes if RTS is enabled. If soomeone wants to use both blockwise and byte-wise reads, then the patch allows to get the orinial behaviour: bytes are received in the provided buffer or in the byte callback. I don't have a good idea, in which situations this might be needed/useful, though.