Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756804Ab0GaVVk (ORCPT ); Sat, 31 Jul 2010 17:21:40 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:61588 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755883Ab0GaVVi (ORCPT ); Sat, 31 Jul 2010 17:21:38 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=qlqgrUTRs1jDuNWz8Y3DNv37jiAvsvo64iNqgke6Rka5OEXyTsx8zGDiKcjuY8aLbV dOvFgAsq5Rez5B6D22A1/3UD7zjAmzoz9wlywjh+cuJj9by2vcDgtoQbjHnOrv8aKbkD KXPaRa1FS8ATncRAow1dCC+eUKrNPHcWEXzyQ= Message-ID: <4C5493DD.7010402@garzik.org> Date: Sat, 31 Jul 2010 17:21:33 -0400 From: Jeff Garzik User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100720 Fedora/3.0.6-1.fc12 Thunderbird/3.0.6 MIME-Version: 1.0 To: Ondrej Zary CC: Russell King - ARM Linux , linux-fbdev@vger.kernel.org, Kernel development list Subject: Re: [PATCH 1/3] cyber2000fb: fix machine hang on module load References: <201007312255.30729.linux@rainbow-software.org> In-Reply-To: <201007312255.30729.linux@rainbow-software.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1408 Lines: 30 On 07/31/2010 04:55 PM, Ondrej Zary wrote: > 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); > } IIRC, cyber2000 is basically an S3 graphics chip. When working on s3fb, over a decade ago, ISTR needing a lot of MMIO register flushes -- dummy register reads -- to flush out just-written register writes. -- 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/