Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754877AbZKFI31 (ORCPT ); Fri, 6 Nov 2009 03:29:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754727AbZKFI31 (ORCPT ); Fri, 6 Nov 2009 03:29:27 -0500 Received: from eddie.linux-mips.org ([78.24.191.182]:42172 "EHLO eddie.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754249AbZKFI30 (ORCPT ); Fri, 6 Nov 2009 03:29:26 -0500 Date: Fri, 6 Nov 2009 09:30:42 +0100 From: Ralf Baechle To: Wu Zhangjin Cc: linux-mips@linux-mips.org, LKML , huhb@lemote.com, yanh@lemote.com, Zhang Le , Thomas Gleixner , Nicholas Mc Guire , zhangfx@lemote.com, liujl@lemote.com Subject: Re: [PATCH -queue v0 4/6] [loongson] add basic fuloong2f support Message-ID: <20091106083042.GA17723@linux-mips.org> References: <0f805f7d12c5a7cbcc125ba4a1b70113ec2047a6.1257325319.git.wuzhangjin@gmail.com> <20091105131603.GA18232@linux-mips.org> <1257485984.2299.21.camel@falcon.domain.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1257485984.2299.21.camel@falcon.domain.org> 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 Content-Length: 1127 Lines: 30 On Fri, Nov 06, 2009 at 01:39:44PM +0800, Wu Zhangjin wrote: > > > + if ((LOONGSON_INTISR & LOONGSON_INTEN) & LOONGSON_INT_BIT_INT0) { > > > + imr = inb(0x21) | (inb(0xa1) << 8); > > > + isr = inb(0x20) | (inb(0xa0) << 8); > > > + isr &= ~0x4; /* irq2 for cascade */ > > > + isr &= ~imr; > > > + irq = ffs(isr) - 1; > > > + } > > > > Any reason why you're not using i8259_irq() from here? > > That function not only gets the locking right, it also minimizes the number > > of accesses to the i8259 - which even on modern silicon can be stuningly > > slow. > Just asked Yanhua, He told me there is a bug in cs5536, if using the > i8259_irq() directly, we can not get the irq. and just tried it, the > kernel hang on booting. Wonderful. Even 30 years after it was built there are still new i8259 bugs :-) This is probably worth a comment in the code. Ralf -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/