On 02/03/2017 01:06 AM, Daniel Vetter wrote: > On Thu, Feb 02, 2017 at 10:25:44AM -0700, Shuah Khan wrote: >> On 02/02/2017 01:32 AM, Jani Nikula wrote: >>> On Thu, 02 Feb 2017, Shuah Khan <shuahkh@xxxxxxxxxxxxxxx> wrote: >>>> Change drm_helper_probe_single_connector_modes() to print an error to >>>> report connector disconnected status instead of a debug message. >>>> >>>> When this condition occurs, application doesn't know the real error and >>>> reports it as driver lacking support for mode setting. Change it to an >>>> error to make it easier to debug. >>> >>> Please explain what makes this condition an error. Connectors get >>> connected and disconnected, business as usual, why should this be an >>> error? >>> >>> BR, >>> Jani. >> >> Disconnecting connector itself isn't an error. When user-space tries >> to access it, it would be useful to report the status that the connector >> is disconnected. >> >> I use embedded system(s) that don't like it when HDMI is hot added or >> removed. Also, because of return power, it is safer to disconnect HDMI >> and then apply power to the board. It chased a few libdrm and user-space >> dead ends before I enabled drm debug and was able to fix the real issue, >> which is a disconnected cable. >> >> User-space prints rather confusing messages as it doesn't really know >> the disconnected status as it isn't returned to it. >> >> I figured it might be a good idea to at least print a message and this can >> be a notice or info instead of an error. I do think its is worth while in >> some cases. > > This sounds like a very specific use-case you have here, and it can easily > be supported by a small deamon in userspace (only on debug builds ofc) > that tell you that someone unplugged the screen when it shouldn't have > been. drm_helper_probe_single_connector_modes() finds the condition and doesn't have a means to return it to the user-space. Instead of error or debug message, would it be useful to add a trace event to report status of connector to drm_helper_probe_single_connector_modes() Trace could be triggered as needed and turned off. Please let me know what you think of this idea? If it sounds useful, I can add it. > > Because upstream runs also on non-embedded systems, where unplugging is > normal, and we definitely don't want to spam dmesg. > -Daniel > thanks, -- Shuah _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
