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

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Message-ID: <1477587370.5295.37.camel@linux.intel.com>
Date:   Thu, 27 Oct 2016 19:56:10 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Ed Blake <ed.blake@...tec.com>, gregkh@...uxfoundation.org
Cc:     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 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.

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)

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy