From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754837Ab1JMLCj (ORCPT ); Thu, 13 Oct 2011 07:02:39 -0400 Received: from bubo.tul.cz ([147.230.16.1]:57588 "EHLO bubo.tul.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752282Ab1JMLCi (ORCPT ); Thu, 13 Oct 2011 07:02:38 -0400 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes Organization: TUL Subject: [RFC][PATCH][TRIVIAL] System ACE fails in look for root devices To: grant.likely@secretlab.ca Date: Thu, 13 Oct 2011 13:02:42 +0200 Cc: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: "Petr Cvek" Message-ID: User-Agent: Opera Mail/10.63 (Linux) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, I sent this mail some time ago, but nobody replied :-(. I'm using microblaze linux on ML506 board and I found problem with SystemACE CF driver. When xsysace driver is probed, and dts file does not include entry "port-number" (existence of line not actually tested) on line: of_property_read_u32(dev->dev.of_node, "port-number", &id); kernel fails to boot with this message: <4>VFS: Cannot open root device "xsa2" or unknown-block(0,0) <4>Please append a correct "root=" boot option; here are the available partitions: <4>fff:ffff0 990864 xs` (driver?) <4> fff:ffff1 124960 xs`1 00000000-0000-0000-0000-000000000000 <4> fff:ffff2 865872 xs`2 00000000-0000-0000-0000-000000000000 <0>Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) (note xs` xs`1 xs`2 partition names) So I've done some searching and found "ace->id" variable, which has value "-1". Because this value define letter of drive and is incremented by 'a', then with its value of -1, creates letter before 'a' thus '`'. "ace->id" value is assigned in ace_probe function on line of_property_read_u32(dev->dev.of_node, "port-number", &id); if (id < 0) id = 0; This condition should prevents value to be less than zero, but is does not. It's because type, which is u32 few lines before, condition is never true. So I suggest changing it to int. Actually, there was patch some time ago, which has changed it into u32 (last patch for xsysace.c). http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=5d10302f46df1d9a85c34ea97f9b6c29e414482e And finally here is my patch, which suggests changing this line back: Test for signed value is never true, because of unsigned type. From: Petr Cvek Signed-off-by: Petr Cvek --- diff --git a/drivers/block/xsysace.c b/drivers/block/xsysace.c index fb1975d..3ed920c 100644 --- a/drivers/block/xsysace.c +++ b/drivers/block/xsysace.c @@ -1155,7 +1155,7 @@ static int __devinit ace_probe(struct platform_device *dev) { resource_size_t physaddr = 0; int bus_width = ACE_BUS_WIDTH_16; /* FIXME: should not be hard coded */ - u32 id = dev->id; + int id = dev->id; int irq = NO_IRQ; int i;