[REGRESSION] drm/etnaviv: command buffer outside valid memory window

[Russell King - ARM Linux admin]

While updating my various systems for the TCP SACK issue, I notice
that while most platforms are happy, the Cubox-i4 is not.  During
boot, we get:

[    0.000000] cma: Reserved 256 MiB at 0x30000000
...
[    0.000000] Kernel command line: console=ttymxc0,115200n8 console=tty1 video=mxcfb0:dev=hdmi root=/dev/nfs rw cma=256M ahci_imx.hotplug=1 splash resume=/dev/sda1
[    0.000000] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
[    0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
[    0.000000] Memory: 1790972K/2097152K available (8471K kernel code, 693K rwdata, 2844K rodata, 500K init, 8062K bss, 44036K reserved, 262144K cma-reserved, 1310720K highmem)
...
[   13.101098] etnaviv-gpu 130000.gpu: command buffer outside valid memory window
[   13.171963] etnaviv-gpu 134000.gpu: command buffer outside valid memory window

and shortly after the login prompt appears, the entire SoC appears to
lock up - it becomes unresponsive on the network, or via serial console
to sysrq requests.

I suspect the GPU ends up scribbling over the CPU's vector page/kernel
as a result of the above two etnaviv errors when Xorg attempts to start
using the GPU.

This used to work, so its a regression.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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