Messages in this thread Patch in this message | | | Date | Thu, 13 Oct 2011 11:29:58 -0600 | From | Grant Likely <> | Subject | Re: [RFC][PATCH][TRIVIAL] System ACE fails in look for root devices |
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On Thu, Oct 13, 2011 at 01:02:42PM +0200, Petr Cvek wrote: > 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;
However, of_property_read_u32() can only accept a u32 value, not an int, so this needs to be solved with two variables to be correct:
int id; u32 tmp; id = dev->id; if (of_property_read_u32(dev->dev.of_node, "port-number", &tmp) id = tmp; if (id < 0) id = 0;
It's not as pretty, but it is a limitation of how of_property_read_u32 has to be implemented. I hope to find a better way to do it that doesn't have the u32 restriction on the return value.
g.
> > 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 <petr.cvek@tul.cz> > > Signed-off-by: Petr Cvek <petr.cvek@tul.cz> > --- > 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; >
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