Public bug reported:
Impact:
There is a kernel hang in 4.4.y if the vc4 driver is enabled, and
another program opens /dev/fb0 to display an image.
Fix:
Apply the attached patch and recompile the kernel.
How to test:
Enable the gpu hardware acceleration by loading the vc4 overlay:
config.txt:
...
dtoverlay=vc4-kms-v3d
...
reboot and check that vc4 was activated:
$ dmesg | grep vc4
...
[ 15.274385] vc4-drm soc:gpu: bound 3f902000.hdmi (ops vc4_hdmi_ops [vc4])
[ 15.274660] vc4_dsi 3f700000.dsi: DSI not set up by firmware.
[ 15.274753] vc4-drm soc:gpu: bound 3f700000.dsi (ops vc4_dsi_ops [vc4])
[ 15.274873] vc4-drm soc:gpu: bound 3f400000.hvs (ops vc4_hvs_ops [vc4])
[ 15.275178] vc4-drm soc:gpu: bound 3f206000.pixelvalve (ops vc4_crtc_ops
[vc4])
[ 15.275407] vc4-drm soc:gpu: bound 3f207000.pixelvalve (ops vc4_crtc_ops
[vc4])
[ 15.275643] vc4-drm soc:gpu: bound 3f807000.pixelvalve (ops vc4_crtc_ops
[vc4])
[ 15.275818] vc4-drm soc:gpu: bound 3fc00000.v3d (ops vc4_v3d_ops [vc4])
[ 15.403354] vc4-drm soc:gpu: fb0: frame buffer device
...
then download and compile psplash:
$ git clone git://git.yoctoproject.org/psplash
$ cd psplash
$ autoreconf --install
$ ./configure
$ make
$ sudo ./psplash
here the board should hang, pull the plug to get it back.
Now install the patched kernel, and execute psplash again - the board will be
fine, and a bitmap will be displayed on hdmi, ctrl+c to exit psplash.
--
** Affects: linux-raspi2 (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1708417
Title:
Board hangs with 'dtoverlay=vc4-kms-v3d' while writing to /dev/fb0
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