Linux-3.14-rc2: Order of serial node compatibles in DTS files.

[Sebastian Hesselbarth]

On 02/12/2014 12:38 AM, Stephen N Chivers wrote:
> Sebastian Hesselbarth <sebastian.hesselbarth at gmail.com> wrote on
>> On 02/11/2014 11:33 PM, Kumar Gala wrote:
>>> On Feb 11, 2014, at 2:57 PM, Stephen N Chivers <schivers at csc.com.au> wrote:
>>>> I have been trial booting a 3.14-rc2 kernel for a 85xx platform
>>>> (dtbImage).
[...]
>>>>
>>>> of_serial f1004500.serial: Unknown serial port found, ignored.
>>>>
>>>> The serial nodes in boards dts file are specified as:
>>>>
>>>>          serial0: serial at 4500 {
>>>>                          cell-index = <0>;
>>>>                          device_type = "serial";
>>>>                          compatible = "fsl,ns16550", "ns16550";
>>>>                          reg = <0x4500 0x100>;
>>>>                          clock-frequency = <0>;
>>>>                          interrupts = <0x2a 0x2>;
>>>>                          interrupt-parent = <&mpic>;
>>>>                  };
>>>
>>> Wondering if this caused the issue:
>>>
>>> commit 105353145eafb3ea919f5cdeb652a9d8f270228e
>>> Author: Sebastian Hesselbarth <sebastian.hesselbarth at gmail.com>
>>> Date:   Tue Dec 3 14:52:00 2013 +0100
>>>
>>>       OF: base: match each node compatible against all given matches first
>>
[...]
>>
>> 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.

I revert my statement about removing anything from of_serial.c. Instead
we should try to prefer matches with compatibles over type/name without
compatibles. Something like the patch below (compile tested only)





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