libddcutil ddca_get_display_info_list2 returns DDCRC_OTHER (-3022)

[digitaltrails]

A ddcutil-service user raised an issue where detect is failing resulting in DDCRC_OTHER (-3022) being returned by ddca_get_display_info_list2().

It appears the user has some non-display i2c devices that cannot be accessed. This causes set_ddca_error_detail_from_open_errors() to return DDCRC_OTHER. Which in turn results in ddca_get_display_info_list2() also returning DDCRC_OTHER even though there are displays in the return list from i2c devices that could be opened. If some devices are in the list, perhaps DDCRC_OTHER is inappropriate, or needs documenting.

I've pushed a change to ddcutil-service that filters DDCRC_OTHER which has fixed the user's issue.

If other projects are using libddcutil, it may be causing them issues as well. KDE PowerDevil comes to mind and, of course, ddcui.

[rockowitz]

Commit b3573c2 changes the behaviour of ddca_get_display_refs() and ddca_get_display_info2() to always return 0 (as documented in ddcutil_c_api.h.)

So that information about errors that occur opening individual displays or reading their EDIDs is not lost, they are still reported using ddca_get_error_detail(). In addition, error messages are written to the terminal (which may or may not exist) and, depending on the current syslog level, to the system log.

[digitaltrails]

Thanks. I modified ddcutil-service to check for either behaviour and issue a warning if encountered and return DDCRC_OK for both.