From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rafal Prylowski Subject: Re: [PATCH v2 1/3] PATA host controller driver for ep93xx Date: Wed, 04 Apr 2012 14:40:34 +0200 Message-ID: <4F7C4142.1010709@metasoft.pl> References: <4F7B0C54.8010804@metasoft.pl> <4F7B0CEF.2040307@metasoft.pl> <201204032008.00509.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit Return-path: Received: from metasoft.pl ([195.149.224.191]:51247 "EHLO smtp.metasoft.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756106Ab2DDMlP (ORCPT ); Wed, 4 Apr 2012 08:41:15 -0400 In-Reply-To: <201204032008.00509.arnd@arndb.de> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Arnd Bergmann Cc: linux-arm-kernel@lists.infradead.org, H Hartley Sweeten , "linux-ide@vger.kernel.org" , Sergei Shtylyov , "bzolnier@gmail.com" , "rmallon@gmail.com" , "joao.ramos@inov.pt" On 2012-04-03 22:08, Arnd Bergmann wrote: >>> +static void ep93xx_pata_wait_for_iordy(void __iomem *base) >>> +{ >>> + unsigned long deadline = jiffies + msecs_to_jiffies(1000); >>> + while (!ep93xx_pata_check_iordy(base) && >>> + time_is_before_jiffies(deadline)) >>> + cpu_relax(); >>> +} > > Much better for a delay than the previous version. However, it's > still a busy wait, which is bad for realtime behavior, especially > since this can potentially take many milliseconds. If possible, > it should have an msleep() or at least cond_resched() instead of > the cpu_relax(). Obviously that will only work when no spinlocks > are held. > Unfortunately, we can't use msleep() or cond_resched() here - ep93xx_pata_wait_for_iordy() is called from interrupt handler. Thanks, RP