Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752889Ab0G0VTL (ORCPT ); Tue, 27 Jul 2010 17:19:11 -0400 Received: from mail1-out1.atlantis.sk ([80.94.52.55]:51319 "EHLO mail.atlantis.sk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750964Ab0G0VTK (ORCPT ); Tue, 27 Jul 2010 17:19:10 -0400 From: Ondrej Zary To: "Russell King - ARM Linux" Subject: Re: [PATCH] [resend] cyber2000fb: fix machine hang on module load Date: Tue, 27 Jul 2010 23:18:55 +0200 User-Agent: KMail/1.9.10 Cc: linux-fbdev@vger.kernel.org, Kernel development list References: <201007271529.22520.linux@rainbow-software.org> <20100727162510.GB17099@n2100.arm.linux.org.uk> In-Reply-To: <20100727162510.GB17099@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <201007272318.57975.linux@rainbow-software.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2017 Lines: 50 On Tuesday 27 July 2010 18:25:11 Russell King - ARM Linux wrote: > On Tue, Jul 27, 2010 at 03:29:20PM +0200, Ondrej Zary wrote: > > Hello, > > I was testing two CyberPro 2000 based PCI cards on x86 and the machine > > always hanged completely when the cyber2000fb module was loaded. It seems > > that the card hangs when some registers are accessed too quickly after > > writing RAMDAC control register. With this patch, both card work. > > > > Add delay after RAMDAC control register write to prevent hangs on module > > load. > > This one on the other hand I think is rather too heavy. > > What might be better is to re-code the last register write to use > the x86 outb_p() stuff to slow it down, rather than using udelay(). > Could you try something along those lines please? Is this better? I was testing two CyberPro 2000 based PCI cards on x86 and the machine always hanged completely when the cyber2000fb module was loaded. It seems that the card hangs when some registers are accessed too quickly after writing RAMDAC control register. With this patch, both card work. Add delay after RAMDAC control register write to prevent hangs on module load. Signed-off-by: Ondrej Zary --- linux-2.6.35-rc2-orig/drivers/video/cyber2000fb.c 2010-06-06 05:43:24.000000000 +0200 +++ linux-2.6.35-rc3/drivers/video/cyber2000fb.c 2010-07-27 23:12:37.000000000 +0200 @@ -436,6 +436,8 @@ static void cyber2000fb_write_ramdac_ctr cyber2000fb_writeb(i | 4, 0x3cf, cfb); cyber2000fb_writeb(val, 0x3c6, cfb); cyber2000fb_writeb(i, 0x3cf, cfb); + /* prevent card lock-up observed on x86 with CyberPro 2000 */ + cyber2000fb_readb(0x3cf, cfb); } static void cyber2000fb_set_timing(struct cfb_info *cfb, struct par_info *hw) -- Ondrej Zary -- 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/