[U-Boot] [PATCH 1/3] test/py: Handle the banner being printed after relocation

[Stephen Warren]

On 07/28/2017 09:57 PM, Simon Glass wrote:
> Hi Stephen,
> 
> On 27 July 2017 at 15:27, Stephen Warren <swarren at wwwdotorg.org> wrote:
>> On 07/27/2017 09:31 AM, Simon Glass wrote:
>>>
>>> If CONFIG_DISPLAY_BOARDINFO_LATE is enabled, U-Boot displays the banner
>>> again after relocation so that it is visible on the video display. Detect
>>> this and allow it.
>>>
>>> Note: This patch is only an interim fix. If it is applied we should
>>> consider reverting it later since it is not needed if U-Boot is working
>>> correctly.
>>
>>
>> It'd be useful if that paragraph could be expanded a bit; what exactly is
>> the bug and how will it be fixed? The situation described in the first
>> paragraph doesn't seem like a bug. Perhaps the fix be to delay the sign-on
>> message until video output is available and only print it once, or not print
>> the sign-on to serial when printing it a second time so that it's seen on
>> video?
> 
> The bug is described /fixed in patches 2 & 3 of this series. I sent
> this patch in case there was urgency in fixing it.
> 
>>
>>> diff --git a/test/py/u_boot_console_base.py
>>> b/test/py/u_boot_console_base.py
>>
>>
>>> @@ -355,12 +355,31 @@ class ConsoleBase(object):
>>>                self.u_boot_version_string = self.p.after
>>>                while True:
>>>                    m = self.p.expect([self.prompt_compiled,
>>> -                    pattern_stop_autoboot_prompt] + self.bad_patterns)
>>> +                    pattern_stop_autoboot_prompt,
>>> pattern_u_boot_main_signon] +
>>> +                    self.bad_patterns)
>>
>>
>> This doesn't seem quite right. At a very high level, the current code does
>> this:
>>
>> 1) If SPL will print a sign-on:
>>       Wait for SPL to print sign-on
>> 2) Wait for main U-Boot to print a sign-on
>> 3) Wait for auto-boot prompt and interrupt it.
>>
>> This change modifies (3) to alternatively wait for another sign-on prompt,
> 
> Well actually the existing code already does this if you look closely.
> If it sees second sign-on it detects this and fails the test
> (presumably because it indicates there was an unexpected reboot).
> Otherwise I would not have bothered with this patch.

But it's doing it in a much more "after-the-fact" and brittle way.

>> which means it's doing 2 unrelated things. Better would be to just add a new
>> standalone step to wait for the extra sign-on message:
>>
>> 1) If SPL will print a sign-on:
>>       Wait for SPL to print sign-on
>> 2) Wait for main U-Boot to print a sign-on
>> 3) If a duplicate sign-on message will be printed:
>>       Wait for duplicate sign-on from main U-Boot
>> 4) Wait for auto-boot prompt and interrupt it.
>>
>> Judging by the code quoted below, new step (3) above can use the value of
>> bcfg.get('config_display_boardinfo_late', 'n') == 'y' to make the decision.
>>
>> That has the advantage of not requiring the following heuristic to
>> differentiate between expected sign-on messages and unexpected sign-on
>> messages due to U-Boot crashing and restarting:
> 
> Yes I think that would work. I did consider making it explicit on that
> option, which is indeed what causes the problem.
> 
> But if there are no objections I think it is best to skip this interim
> patch and apply the real fix (patches 2, 3) once they get some review.

Yes, if patches 2/3 fix the root-cause, then I'd agree let's just apply 
those instead.