Board hangs with 'dtoverlay=vc4-kms-v3d' while writing to /dev/fb0

[Paolo Pisati]

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.

--

[Kleber Sacilotto de Souza (kleber-souza)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-xenial' to 'verification-done-xenial'. If the problem still exists, change the tag 'verification-needed-xenial' to 'verification-failed-xenial'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-raspi2 - 4.4.0-1071.79

---------------
linux-raspi2 (4.4.0-1071.79) xenial; urgency=low

  * linux-raspi2: 4.4.0-1071.79 -proposed tracker (LP: #1709298)

  * Board hangs with 'dtoverlay=vc4-kms-v3d' while writing to /dev/fb0
    (LP: #1708417)
    - drm/fb_cma_helper: Implement fb_mmap callback

  * Snapcraft.yaml update (LP: #1700577)
    - snapcraft.yaml: various improvements

  [ Ubuntu: 4.4.0-93.116 ]

  * linux: 4.4.0-93.116 -proposed tracker (LP: #1709296)
  * Creating conntrack entry failure with kernel 4.4.0-89 (LP: #1709032)
    - Revert "Revert "netfilter: synproxy: fix conntrackd interaction""
    - netfilter: nf_ct_ext: fix possible panic after nf_ct_extend_unregister
  * CVE-2017-1000112
    - Revert "udp: consistently apply ufo or fragmentation"
    - udp: consistently apply ufo or fragmentation
  * CVE-2017-1000111
    - Revert "net-packet: fix race in packet_set_ring on PACKET_RESERVE"
    - packet: fix tp_reserve race in packet_set_ring
  * kernel BUG at [tty_ldisc_reinit] mm/slub.c! (LP: #1709126)
    - tty: Simplify tty_set_ldisc() exit handling
    - tty: Reset c_line from driver's init_termios
    - tty: Handle NULL tty->ldisc
    - tty: Move tty_ldisc_kill()
    - tty: Use 'disc' for line discipline index name
    - tty: Refactor tty_ldisc_reinit() for reuse
    - tty: Destroy ldisc instance on hangup
  * atheros bt failed after S3 (LP: #1706833)
    - SAUCE: Bluetooth: Make request workqueue freezable
  * The Precision Touchpad(PTP) button sends incorrect event code (LP: #1708372)
    - HID: multitouch: handle external buttons for Precision Touchpads
  * Set CONFIG_SATA_HIGHBANK=y on armhf (LP: #1703430)
    - [Config] CONFIG_SATA_HIGHBANK=y
  * xfs slab objects (memory) leak when xfs shutdown is called (LP: #1706132)
    - xfs: fix xfs_log_ticket leak in xfs_end_io() after fs shutdown
  * Adt tests of src:linux time out often on armhf lxc containers (LP: #1705495)
    - [Packaging] tests -- reduce rebuild test to one flavour
  * CVE-2017-7495
    - ext4: fix data exposure after a crash
  * ubuntu/rsi driver downlink wifi throughput drops to 5-6 Mbps when BT
    keyboard is connected (LP: #1706991)
    - SAUCE: Redpine: enable power save by default for coex mode
    - SAUCE: Redpine: uapsd configuration changes
  * [Hyper-V] hv_netvsc: Exclude non-TCP port numbers from vRSS hashing
    (LP: #1690174)
    - hv_netvsc: Exclude non-TCP port numbers from vRSS hashing
  * ath10k doesn't report full RSSI information (LP: #1706531)
    - ath10k: add per chain RSSI reporting
  * ideapad_laptop don't support v310-14isk (LP: #1705378)
    - platform/x86: ideapad-laptop: Add several models to no_hw_rfkill
  * [8087:0a2b] Failed to load bluetooth firmware(might affect some other Intel
    bt devices) (LP: #1705633)
    - Bluetooth: btintel: Create common Intel Version Read function
    - Bluetooth: Use switch statement for Intel hardware variants
    - Bluetooth: Replace constant hw_variant from Intel Bluetooth firmware
      filename
    - Bluetooth: hci_intel: Fix firmware file name to use hw_variant
    - Bluetooth: btintel: Add MODULE_FIRMWARE entries for iBT 3.5 controllers
  * xhci_hc...