linux-kernel - Re: [PATCH] usb: musb: da8xx: Don't print phy error on -EPROBE

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Date:   Thu, 3 Nov 2016 10:42:17 -0500
From:   Bin Liu <b-liu@...com>
To:     Ladislav Michl <ladis@...ux-mips.org>
CC:     David Lechner <david@...hnology.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexandre Bailon <abailon@...libre.com>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: musb: da8xx: Don't print phy error on -EPROBE_DEFER

On Wed, Nov 02, 2016 at 10:45:59PM +0100, Ladislav Michl wrote:
> Hi,
> 
> On Tue, Oct 25, 2016 at 02:02:50PM -0500, David Lechner wrote:
> > This suppresses printing the error message "failed to get phy" in the
> > kernel log when the error is -EPROBE_DEFER. This prevents usless noise
> > in the kernel log.
> > 
> > Signed-off-by: David Lechner <david@...hnology.com>
> > ---
> >  drivers/usb/musb/da8xx.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/usb/musb/da8xx.c b/drivers/usb/musb/da8xx.c
> > index 481d786..f8a1591 100644
> > --- a/drivers/usb/musb/da8xx.c
> > +++ b/drivers/usb/musb/da8xx.c
> > @@ -516,7 +516,8 @@ static int da8xx_probe(struct platform_device *pdev)
> >  
> >  	glue->phy = devm_phy_get(&pdev->dev, "usb-phy");
> >  	if (IS_ERR(glue->phy)) {
> > -		dev_err(&pdev->dev, "failed to get phy\n");
> > +		if (PTR_ERR(glue->phy) != -EPROBE_DEFER)
> > +			dev_err(&pdev->dev, "failed to get phy\n");
> 
> What about something like this?
> 
> dev_printk(PTR_ERR(glue->phy) == -EPROBE_DEFER ? KERN_DEBUG : KERN_ERR, ...
> 
> At least it outputs something if debug is enabled, making debugging easier.

It is unnecessary, when probe failed, kernel prints a probe failure log
with error -517, and da8xx_probe() has only this one place returning
-EPROBE_DEFER.

And this change makes the code a little hard to read.

Regards,
-Bin.