linux-kernel - Re: [PATCH 1/2] tty/serial: atmel: Add is_half

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Date:   Mon, 18 Mar 2019 14:17:34 +0000
From:   <Razvan.Stefanescu@...rochip.com>
To:     <richard.genoud@...il.com>, <gregkh@...uxfoundation.org>,
        <jslaby@...e.com>
CC:     <webergil@...il.com>, <Nicolas.Ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>, <Ludovic.Desroches@...rochip.com>,
        <linux-serial@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] tty/serial: atmel: Add is_half_duplex helper



On 18/03/2019 15:41, Richard Genoud wrote:
> [ adding Gil Weber in Cc: ]
> 
> Le 15/03/2019 à 10:23, Razvan Stefanescu a écrit :
>> Use a helper function to check that a port needs to use half duplex
>> communication, replacing several occurrences of multi-line bit checking.
>>
>> Signed-off-by: Razvan Stefanescu <razvan.stefanescu@...rochip.com>
>> ---
>>   drivers/tty/serial/atmel_serial.c | 27 ++++++++++++++-------------
>>   1 file changed, 14 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
>> index 05147fe24343..a6577b1c4461 100644
>> --- a/drivers/tty/serial/atmel_serial.c
>> +++ b/drivers/tty/serial/atmel_serial.c
>> @@ -231,6 +231,13 @@ static inline void atmel_uart_write_char(struct uart_port *port, u8 value)
>>   	__raw_writeb(value, port->membase + ATMEL_US_THR);
>>   }
>>   
>> +static inline int atmel_uart_is_half_duplex(struct uart_port *port)
>> +{
>> +	return ((port->rs485.flags & SER_RS485_ENABLED) &&
>> +		!(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
>> +		(port->iso7816.flags & SER_ISO7816_ENABLED);
>> +}
>> +
>>   #ifdef CONFIG_SERIAL_ATMEL_PDC
>>   static bool atmel_use_pdc_rx(struct uart_port *port)
>>   {
>> @@ -608,10 +615,10 @@ static void atmel_stop_tx(struct uart_port *port)
>>   	/* Disable interrupts */
>>   	atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
>>   
>> -	if (((port->rs485.flags & SER_RS485_ENABLED) &&
>> -	     !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
>> -	    port->iso7816.flags & SER_ISO7816_ENABLED)
>> -		atmel_start_rx(port);
>> +	if (atmel_uart_is_half_duplex(port))
>> +		if (!atomic_read(&atmel_port->tasklet_shutdown))
> This check wasn't there before.
> If it's really needed, please insert it in another patch and explain why
> it's needed.
> 
Thank you for the feedback. It is not needed, will be removed in v2.

Best regards,
Razvan

>> +			atmel_start_rx(port);
>> +
>>   }
>>   
>>   /*
>> @@ -628,9 +635,7 @@ static void atmel_start_tx(struct uart_port *port)
>>   		return;
>>   
>>   	if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port))
>> -		if (((port->rs485.flags & SER_RS485_ENABLED) &&
>> -		     !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
>> -		    port->iso7816.flags & SER_ISO7816_ENABLED)
>> +		if (atmel_uart_is_half_duplex(port))
>>   			atmel_stop_rx(port);
>>   
>>   	if (atmel_use_pdc_tx(port))
>> @@ -928,9 +933,7 @@ static void atmel_complete_tx_dma(void *arg)
>>   	 */
>>   	if (!uart_circ_empty(xmit))
>>   		atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
>> -	else if (((port->rs485.flags & SER_RS485_ENABLED) &&
>> -		  !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
>> -		 port->iso7816.flags & SER_ISO7816_ENABLED) {
>> +	else if (atmel_uart_is_half_duplex(port)) {
>>   		/* DMA done, stop TX, start RX for RS485 */
>>   		atmel_start_rx(port);
>>   	}
>> @@ -1508,9 +1511,7 @@ static void atmel_tx_pdc(struct uart_port *port)
>>   		atmel_uart_writel(port, ATMEL_US_IER,
>>   				  atmel_port->tx_done_mask);
>>   	} else {
>> -		if (((port->rs485.flags & SER_RS485_ENABLED) &&
>> -		     !(port->rs485.flags & SER_RS485_RX_DURING_TX)) ||
>> -		    port->iso7816.flags & SER_ISO7816_ENABLED) {
>> +		if (atmel_uart_is_half_duplex(port)) {
>>   			/* DMA done, stop TX, start RX for RS485 */
>>   			atmel_start_rx(port);
>>   		}
>>
>