linux-kernel - RE: [PATCH] serial: fsl_lpuart: Remove the alias node dependence

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Date:   Thu, 12 Jan 2017 02:27:45 +0000
From:   Yao Yuan <yao.yuan@....com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Yuan Yao <yao.yuan@...escale.com>
CC:     "jslaby@...e.com" <jslaby@...e.com>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] serial: fsl_lpuart: Remove the alias node dependence

On Wed, Jan 11, 2016 at 04:33:32PM +0800, Greg KH wrote:
> On Wed, Dec 14, 2016 at 04:33:32PM +0800, Yuan Yao wrote:
> > From: Yuan Yao <yao.yuan@....com>
> >
> > Numbering the ttyLPn space should not depend on the generic name
> > "serial<n>".
> >
> > If don't add the alias node like:"serial0 = &lpuart0;", then lpuart
> > will probe failed:
> > [    0.773410] fsl-lpuart 2950000.serial: failed to get alias id, errno -19
> >
> > So remove the alias node dependence, and add the support for allocate
> > the line port automatically.
> >
> > Signed-off-by: Yuan Yao <yao.yuan@....com>
> > ---
> >  drivers/tty/serial/fsl_lpuart.c | 11 +++++++++--
> >  1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/tty/serial/fsl_lpuart.c
> > b/drivers/tty/serial/fsl_lpuart.c index a1c6519..c6d639f 100644
> > --- a/drivers/tty/serial/fsl_lpuart.c
> > +++ b/drivers/tty/serial/fsl_lpuart.c
> > @@ -231,6 +231,8 @@
> >  #define DEV_NAME	"ttyLP"
> >  #define UART_NR		6
> >
> > +static DECLARE_BITMAP(linemap, UART_NR);
> 
> Why a bitmap?

Because I think the bitmap is enough to meet the need.
Are there any shortcomings for bitmap used here?

> 
> > +
> >  struct lpuart_port {
> >  	struct uart_port	port;
> >  	struct clk		*clk;
> > @@ -1963,9 +1965,13 @@ static int lpuart_probe(struct platform_device
> > *pdev)
> >
> >  	ret = of_alias_get_id(np, "serial");
> >  	if (ret < 0) {
> > -		dev_err(&pdev->dev, "failed to get alias id, errno %d\n", ret);
> > -		return ret;
> > +		ret = find_first_zero_bit(linemap, UART_NR);
> > +		if (ret >= UART_NR) {
> > +			dev_err(&pdev->dev, "port line is full, add device
> failed\n");
> > +			return ret;
> > +		}
> 
> Does this really remove the alias dependancy?
> 
> Please use an idr or ida for this instead of a bitmap.
> 

Hi Greg,

Thanks for your review.

Is there any advantage for use an idr or ida instead of bitmap?
I will hope to get your guidance.

Thanks.