From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753883Ab2A1QBE (ORCPT ); Sat, 28 Jan 2012 11:01:04 -0500 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:53688 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753076Ab2A1QBB (ORCPT ); Sat, 28 Jan 2012 11:01:01 -0500 Date: Sat, 28 Jan 2012 16:00:11 +0000 From: Russell King - ARM Linux To: Roland Stigge Cc: w.sang@pengutronix.de, grant.likely@secretlab.ca, linus.walleij@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Fix LPC32XX's clock.c Message-ID: <20120128160011.GA15455@n2100.arm.linux.org.uk> References: <1327673868-19741-1-git-send-email-stigge@antcom.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1327673868-19741-1-git-send-email-stigge@antcom.de> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 27, 2012 at 03:17:48PM +0100, Roland Stigge wrote: > @@ -382,30 +388,62 @@ static u32 local_clk_usbpll_setup(struct clk_pll_setup *pHCLKPllSetup) > static int local_usbpll_enable(struct clk *clk, int enable) > { > u32 reg; > - int ret = -ENODEV; > - unsigned long timeout = 1 + msecs_to_jiffies(10); > + int ret = 0; > + unsigned long timeout = jiffies + msecs_to_jiffies(20); ... > - /* Wait for PLL lock */ > - while ((timeout > jiffies) & (ret == -ENODEV)) { > + /* > + * Enable PLL > + */ > + reg |= LPC32XX_CLKPWR_USBCTRL_PLL_PWRUP; > + __raw_writel(reg, LPC32XX_CLKPWR_USB_CTRL); > + > + /* > + * Wait for PLL to lock > + */ > + while ((timeout > jiffies) && (ret == -ENODEV)) { This is buggy - it's waiting to go wrong when jiffies wraps. You really want to use time_before() or time_after() to make these comparisons, which are safe against wrap-around.