[U-Boot] [PATCH v4 2/2] splash: add support for loading splash from a FIT image

[Tomas Melin]

Hi Igor, Simon,

On 12/15/2016 11:08 AM, Igor Grinberg wrote:
> Hi Tomas,
> 
> On 12/14/16 16:23, Tomas Melin wrote:
>> Hi Simon, Igor,
>>
>> On 12/14/2016 02:53 PM, Igor Grinberg wrote:
>>> On 12/13/16 22:29, Simon Glass wrote:
>>>>>>>
>>>>>>> I think two above debug() are very legitimate - no need to shout if no FIT image
>>>>>>> or no splash in it...
>>>>>>>
>>>>>>>> +     res = fit_image_get_data_offset(fit_header, node_offset,
>>>>>>>> +                                     &splash_offset);
>>>>>>>> +     if (res < 0) {
>>>>>>>> +             debug("Could not find 'data-offset' property in FIT\n");
>>>>>>>> +             return res;
>>>>>>>> +     }
>>>>>>>> +
>>>>>>>> +     res = fit_image_get_data_size(fit_header, node_offset, &splash_size);
>>>>>>>> +     if (res < 0) {
>>>>>>>> +             debug("Could not find 'data-size' property in FIT\n");
>>>>>>>> +             return res;
>>>>>>>> +     }
>>>>>>>
>>>>>>> Now regarding these two, I'm not sure.
>>>>>>> Since we have found a valid FIT and also a node with a correct splash name,
>>>>>>> probably the intent is that we show the splash, right?
>>>>>>> But in the two above checks, we find inconsistencies that do not allow us to
>>>>>>> show the splash - meaning the FIT is not actually good (am I right here?).
>>>>>>> So may be we should report it to the 'user' and allow correcting the FIT?
>>>>>>> Otherwise, it is impossible to debug the image w/o a debug version of U-Boot...
>>>>>>> Do I make sense, or do I miss something?
>>>>>>
>>>>>> Yes that makes some sense, but the problem is that then you are
>>>>>> including error messages always which would never happen in a working
>>>>>> system (i.e. it just bloats the code).
>>>>>
>>>>> Unless, there a kind of corruption or a user mistake and then that same
>>>>> user can't even understand what happened because we do not help him with
>>>>> an error message.
>>>>> You cannot know that these error messages will never happen...
>>>>> This is a generic code which can be used by a wide variety of platforms -
>>>>> I don't think you can foresee all the possible use cases.
>>>>>
>>>>> We are talking about several tens of bytes vs. usability.
>>>>> If there is an error, it should be stated as such. It should not just
>>>>> exit silently...
>>>>
>>>> I agree with that, there should definitely be an error printed. It
>>>> should say something like 'Failed to load splash screen (err=-4)' or
>>>> something like that. The error number should provide some clues and
>>>> people can dig in.
>>>
>>> Great idea!
>>
>> splash_load_fit() currently fails silently but still reports the error in
>> the return value. And this function is used so that board.c calls 
>> splash_source_load()->splash_load_fit().
>> The board function call will get notified of the error value as provided
>> by the return value for splash_load_fit(). In our board implementation that is 
>> actually exactly how it is done, the board function call checks the return
>> value and prints ("Failed to load splash screen image, error: %d\n", ret)
>> in case there was and error.
>>
>> IMHO this is quite good behaviour as is, leaving it up to the implementation
>> in the board.c if there should be a error message or not (and if it should 
>> bloat the code with another printf or not).
> 
> Well, yes this makes sense if you care to do the work in the board code.
> Although, I would expect that sometime this code will be called from
> a generic board independent place (e.g. init array, etc.).

I don't have a strong opinion, even if I do prefer the current version.
Please let me know if patch this still needs changes. 

BR,
Tomas