Re: [REGRESSION] "of: Fix premature bootconsole disable with 'stdout-path'" breaks console on tty0

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 16-03-15 19:23, Peter Hurley wrote:
> On 03/16/2015 02:12 PM, Hans de Goede wrote:
>> Hi,
>>
>> On 16-03-15 18:49, Peter Hurley wrote:
>>> Hi Hans,
>>>
>>> On 03/16/2015 12:31 PM, Hans de Goede wrote:
>>>> Hi All,
>>>>
>>>> While updating my local working tree to 4.0-rc4 this morning I noticed that I no longer
>>>> get console / kernel messages output on the hdmi output of my ARM board / on tty0
>>>>
>>>> This is caused by:
>>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/of?id=2fa645cb2703d9b3786d850db815414dfeefa51d
>>>>
>>>> Reverting this commit fixes this for me.
>>>>
>>>> What is happening here is that the "add_preferred_console("stdout-path", 0, NULL);"
>>>> happens before the tty0 registers stopping tty0 from becoming part of the console list
>>>> since there already is a preferred console at that time.
>>>>
>>>> This is an undesirable behavior change caused by the commit in question, on boards
>>>> where there is both video output, and a serial console configured through stdout-path
>>>> we want to have console output on both as we do not know which of the 2 will actually
>>>> be hooked up by the user.
>>>
>>> I don't see this as a regression, but rather a misconfiguration.
>>
>> As said it is an undesirable behavior change, whether you want to call that a regression
>> or not is not all that interesting. Fixing it however is important, as e.g. Fedora
>> ARM images rely on this behavior, both "regular" arm as well as aarch64.
>
> What dts file is causing this problem?
> Is it in mainline or distributed only in Fedora?

This is on allwinner (sunxi) devices such as Allwinner A10 or A20 based boards, currently
the setting of stdout-path on these boards is done by (an unmodified) upstream u-boot.

To be clear about my aarch64 remark, that relates to the behavior of aarch64 acpi using
machines, those will also output to both a serial tty and tty0 when the acpi equivalent
of stdout-path is present and points to a serial tty.

Regards,

Hans