mirror of https://gitee.com/openkylin/linux.git
c3c296b069
When the usual fbcon legacy options are enabled we have
->register_framebuffer
->fb notifier chain calls into fbcon
->fbcon sets up console on new fbi
->fbi->set_par
->drm_fb_helper_set_par exercises full kms api
And because of locking inversion hilarity all of register_framebuffer
is done with the console lock held. Which means that the first time on
driver load we exercise _all_ the kms code (all probe paths and
modeset paths for everything connected) is under the console lock.
That means if anything goes belly-up in that big pile of code nothing
ever reaches logfiles (and the machine is dead).
Usual tactic to debug that is to temporarily remove those console_lock
calls to be able to capture backtraces. I'm fed up writing this patch
and recompiling kernels. Hence this patch here to add an unsafe,
kernel-taining option to do this at runtime.
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: linux-fbdev@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
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|---|---|---|
| .. | ||
| backlight | ||
| console | ||
| fbdev | ||
| logo | ||
| Kconfig | ||
| Makefile | ||
| display_timing.c | ||
| hdmi.c | ||
| of_display_timing.c | ||
| of_videomode.c | ||
| vgastate.c | ||
| videomode.c | ||