Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx> wrote on
02/12/2014 09:51:43 AM:
> From: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
> To: Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx>, Stephen N Chivers
> <schivers@xxxxxxxxxx>
> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx, Chris Proctor
> <cproctor@xxxxxxxxxx>, devicetree <devicetree@xxxxxxxxxxxxxxx>, Arnd
> Bergmann <arnd@xxxxxxxx>
> Date: 02/12/2014 09:51 AM
> Subject: Re: Linux-3.14-rc2: Order of serial node compatibles in DTS
files.
>
> On 02/11/2014 11:33 PM, Kumar Gala wrote:
> >
> > On Feb 11, 2014, at 2:57 PM, Stephen N Chivers <schivers@xxxxxxxxxx>
wrote:
> >
> >> I have been trial booting a 3.14-rc2 kernel for a 85xx platform
> >> (dtbImage).
> >>
> >> After mounting the root filesystem there are no messages from the
init
> >> scripts
> >> and the serial console is not available for login.
> >>
> >> In the kernel log messages there is:
> >>
> >> of_serial f1004500.serial: Unknown serial port found, ignored.
> >>
> >> The serial nodes in boards dts file are specified as:
> >>
> >> serial0: serial@4500 {
> >> cell-index = <0>;
> >> device_type = "serial";
> >> compatible = "fsl,ns16550", "ns16550";
> >> reg = <0x4500 0x100>;
> >> clock-frequency = <0>;
> >> interrupts = <0x2a 0x2>;
> >> interrupt-parent = <&mpic>;
> >> };
> >>
> >> Reversing the order of the compatible:
> >>
> >> compatible = "ns16550", "fsl,ns16550";
> >>
> >> restores the serial console.
> >>
> >> Linux-3.13 does not have this behaviour.
> >>
> >> There are 49 dts files in Linux-3.14-rc2 that have the fsl,ns16550
> >> compatible first.
> >
> > Hmm,
> >
> > Wondering if this caused the issue:
> >
> > commit 105353145eafb3ea919f5cdeb652a9d8f270228e
> > Author: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
> > Date: Tue Dec 3 14:52:00 2013 +0100
> >
> > OF: base: match each node compatible against all given matches
first
>
> [adding Arnd on Cc]
>
> Could be. I checked tty/serial/of_serial.c and it does not provide a
> compatible for "fsl,ns16550". Does reverting the patch fix the issue
> observed?
>
> I don't think the missing compatible is causing it, but of_serial
> provides a DT match for .type = "serial" just to fail later on
> with the error seen above.
>
> The commit in question reorders of_match_device in a way that match
> table order is not relevant anymore. This can cause it to match
> .type = "serial" first here.
>
> Rather than touching the commit, I suggest to remove the problematic
> .type = "serial" from the match table. It is of no use anyway.
Deleting the "serial" line from the match table fixes the problem.
I tested it for both orderings of compatible.
>
> Sebastian
Thanks,
Stephen Chivers,
CSC Australia Pty. Ltd.
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