Whats missing in my new FB DRM driver... "No connectors reported connected with modes"?

[Daniel Stone]

Hey,

On 22 January 2016 at 07:41, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Thu, Jan 21, 2016 at 7:09 PM, Carlos Palminha
> <CARLOS.PALMINHA at synopsys.com> wrote:
>> i made some progress in identifying the issue...
>> When my driver calls drm_fb_helper_initial_config it seems DRM blocks waiting for register_framebuffer to return.
>> The sequence is drm_fb_helper_initial_config->drm_fb_helper_single_fb_probe->register_framebuffer.
>>
>> Its strange because register_framebuffer function is just a mutex around do_register_framebuffer.
>>
>> Any clue?!
>
> Ah, the curse of console_lock. drm_fb_helper_initial_config also does
> the initial modeset if you have fbcon enabled. But because of locking
> stupidity we must do _all_ that code (which means pretty much your
> entire driver) under the console_lock, which means no log output until
> console_unlock. Not even on serial port.
>
> https://patchwork.freedesktop.org/patch/57951/ is the usual hack to
> use to get rid of console_lock while booting, so that you can see
> where your driver crashes. I guess we should explain this in the
> kerneldoc ...

Didn't spot this at the time, but that should probably quash the
WARN_ON_CONSOLE_UNLOCKED warnings as well ...

Cheers,
Dan