Re: [PATCH v3] serial: stm32: Merge hard IRQ and threaded IRQ handling into single IRQ handler

[Marek Vasut <marex@denx.de>]

On 12/27/22 15:56, Johan Hovold wrote:

[...]

>> @@ -793,27 +794,13 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
>>   	}
>>   
>>   	if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch)) {
>> -		spin_lock(&port->lock);
>> +		spin_lock_irqsave(&port->lock, flags);
>>   		stm32_usart_transmit_chars(port);
>> -		spin_unlock(&port->lock);
>> +		spin_unlock_irqrestore(&port->lock, flags);
> 
> This is not needed as the handler runs with interrupts disabled.

On SMP system, another thread on another core can call 
stm32_usart_transmit_chars() . I don't think removing the locking is 
correct ?

> 
>>   	}
>>   
>> -	if (stm32_usart_rx_dma_enabled(port))
>> -		return IRQ_WAKE_THREAD;
>> -	else
>> -		return IRQ_HANDLED;
>> -}
>> -
>> -static irqreturn_t stm32_usart_threaded_interrupt(int irq, void *ptr)
>> -{
>> -	struct uart_port *port = ptr;
>> -	struct tty_port *tport = &port->state->port;
>> -	struct stm32_port *stm32_port = to_stm32_port(port);
>> -	unsigned int size;
>> -	unsigned long flags;
>> -
>>   	/* Receiver timeout irq for DMA RX */
>> -	if (!stm32_port->throttled) {
>> +	if (stm32_usart_rx_dma_enabled(port) && !stm32_port->throttled) {
>>   		spin_lock_irqsave(&port->lock, flags);
> 
> But you could change this to spin_lock() now.

[...]