From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marek Vasut <marex@denx.de>
Date: Thu, 18 Oct 2012 09:15:49 +0200
Subject: [U-Boot] [PATCH] powerpc/usb: fix bug of CPU hang when missing
	USB PHY clock
In-Reply-To: <3F453DDFF675A64A89321A1F3528102182BFCD@039-SN1MPN1-003.039d.mgd.msft.net>
References: <1350528023-17907-1-git-send-email-Shengzhou.Liu@freescale.com>
	<201210180621.57010.marex@denx.de>
	<3F453DDFF675A64A89321A1F3528102182BFCD@039-SN1MPN1-003.039d.mgd.msft.net>
Message-ID: <201210180915.49387.marex@denx.de>
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Dear Liu Shengzhou-B36685,

> > -----Original Message-----
> > 
> > > +/* Check USB PHY clock valid */
> > > +static int usb_phy_clk_valid(struct usb_ehci *ehci) {
> > > +	if ((!(in_be32(&ehci->control) & PHY_CLK_VALID)) &&
> > > +			(!in_be32(&ehci->prictrl))) {
> > 
> > (!A && !B) condition can certainly be done without the double negation
> > ;-)
> 
> [Shengzhou] Yes, using !(A||B) is also okay:)

Good, you did your logic homework well. Now go one step further:

if (a || b)
 return 1;

printf()
return 0;

How will that work?

> 
> > > +		printf("USB PHY clock invalid!\n");
> > 
> > debug() ?
> 
> [Shengzhou] No, it's not for debug purpose, it should be printf() as a
> necessary info.

OK.

Best regards,
Marek Vasut