On Thu, Jan 21, 2016 at 7:09 PM, Carlos Palminha
[off-list ref] 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 ...
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch