linux-kernel - Re: [PATCH 2/2] serial: 8250_dw: Add support for IrDA SIR mode

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Date:   Thu, 27 Oct 2016 18:33:45 +0100
From:   Ed Blake <ed.blake@...tec.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     <gregkh@...uxfoundation.org>, <jslaby@...e.com>,
        <wangkefeng.wang@...wei.com>, <heikki.krogerus@...ux.intel.com>,
        <noamc@...hip.com>, <annie.wang@....com>,
        <linux-serial@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <james.hartley@...tec.com>
Subject: Re: [PATCH 2/2] serial: 8250_dw: Add support for IrDA SIR mode

On 10/27/16 17:56, Andy Shevchenko wrote:
> On Thu, 2016-10-27 at 17:38 +0100, Ed Blake wrote:
>> Add a set_ldisc function to enable/disable IrDA SIR mode according to
>> the new line discipline.
> Thanks for the patch.
>
> Consider that not all implementations based on 8250_dw support IRDA
> feature. I suppose you need to read capability register bits 6 and 7,
> set flag and then based on the value accept or reject IRDA mode.

Thanks for the review, I'll add this for the second version.

Ed.

>
> P.S. Use -n when prepare patches to link them if you consider them
> dependent.
>
>> Signed-off-by: Ed Blake <ed.blake@...tec.com>
>> ---
>>   drivers/tty/serial/8250/8250_dw.c | 17 +++++++++++++++++
>>   1 file changed, 17 insertions(+)
>>
>> diff --git a/drivers/tty/serial/8250/8250_dw.c
>> b/drivers/tty/serial/8250/8250_dw.c
>> index 459d726..7dd5369 100644
>> --- a/drivers/tty/serial/8250/8250_dw.c
>> +++ b/drivers/tty/serial/8250/8250_dw.c
>> @@ -53,6 +53,8 @@
>>   /* Helper for fifo size calculation */
>>   #define DW_UART_CPR_FIFO_SIZE(a)	(((a >> 16) & 0xff) * 16)
>>   
>> +/* DesignWare specific register fields */
>> +#define DW_UART_MCR_SIRE		BIT(6)
>>   
>>   struct dw8250_data {
>>   	u8			usr_reg;
>> @@ -254,6 +256,20 @@ static void dw8250_set_termios(struct uart_port
>> *p, struct ktermios *termios,
>>   	serial8250_do_set_termios(p, termios, old);
>>   }
>>   
>> +static void dw8250_set_ldisc(struct uart_port *p, struct ktermios
>> *termios)
>> +{
>> +	unsigned int mcr = p->serial_in(p, UART_MCR);
>> +
>> +	if (termios->c_line == N_IRDA)
>> +		mcr |= DW_UART_MCR_SIRE;
>> +	else
>> +		mcr &= ~DW_UART_MCR_SIRE;
>> +
>> +	p->serial_out(p, UART_MCR, mcr);
>> +
>> +	serial8250_do_set_ldisc(p, termios);
>> +}
>> +
>>   /*
>>    * dw8250_fallback_dma_filter will prevent the UART from getting just
>> any free
>>    * channel on platforms that have DMA engines, but don't have any
>> channels
>> @@ -392,6 +408,7 @@ static int dw8250_probe(struct platform_device
>> *pdev)
>>   	p->iotype	= UPIO_MEM;
>>   	p->serial_in	= dw8250_serial_in;
>>   	p->serial_out	= dw8250_serial_out;
>> +	p->set_ldisc	= dw8250_set_ldisc;
>>   
>>   	p->membase = devm_ioremap(dev, regs->start,
>> resource_size(regs));
>>   	if (!p->membase)