Re: [PATCH tty-next v3 4/6] serial: 8250: Specify console context for rs485_start/stop_tx

[Jiri Slaby <jirislaby@kernel.org>]

On 25. 10. 24, 12:57, John Ogness wrote:
> For RS485 mode, if SER_RS485_RX_DURING_TX is not available, the
> console write callback needs to enable/disable TX. It does this
> by calling the rs485_start/stop_tx() callbacks. However, these
> callbacks will disable/enable interrupts, which is a problem
> for console write, as it must be responsible for
> disabling/enabling interrupts.
> 
> Add an argument @in_con to the rs485_start/stop_tx() callbacks
> to specify if they are being called from console write. If so,
> the callbacks will not handle interrupt disabling/enabling.
> 
> For all call sites other than console write, there is no
> functional change.
> 
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
...
> @@ -1562,12 +1566,20 @@ static inline void __start_tx(struct uart_port *port)
>    * stoppable by disabling the UART_IER_RDI interrupt.  (Some chips set the
>    * UART_LSR_DR bit even when UART_IER_RDI is disabled, foiling this approach.)
>    */
> -void serial8250_em485_start_tx(struct uart_8250_port *up)
> +void serial8250_em485_start_tx(struct uart_8250_port *up, bool in_con)
>   {
>   	unsigned char mcr = serial8250_in_MCR(up);
>   
> -	if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
> -		serial8250_stop_rx(&up->port);
> +	if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
> +		/*
> +		 * In console context, caller handles interrupt disabling. So
> +		 * only LSR_DR masking is needed.
> +		 */
> +		if (in_con)
> +			__serial8250_stop_rx_mask_dr(&up->port);
> +		else
> +			serial8250_stop_rx(&up->port);

Would it make sense to propagate in_con into serial8250_stop_rx() and do 
the logic there? That would effectively eliminate patch 2/6.

thanks,
-- 
js
suse labs