kern/52508: radeondrmkmsfb has issues on CEDAR 0x1002:0x68E0 0x1025:0x0347

[martin%NetBSD.org@localhost]

>Number:         52508
>Category:       kern
>Synopsis:       radeondrmkmsfb has issues on CEDAR 0x1002:0x68E0 0x1025:0x0347
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Aug 28 08:15:00 +0000 2017
>Originator:     Martin Husemann
>Release:        NetBSD 8.99.1
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD night-owl.duskware.de 8.99.1 NetBSD 8.99.1 (NIGHT-OWL) #535: Fri Aug 25 17:24:53 CEST 2017 martin%night-owl.duskware.de@localhost:/usr/src/sys/arch/amd64/compile/NIGHT-OWL amd64
Architecture: x86_64
Machine: amd64
>Description:

When using a window manage with compositing, e.g. XFce4 in the default
setup, there are visible artefacts and (in the order of seconds) delayed
redraws of screen parts during every day use. Worse: when running something
that scrolls quickly (like rxvt and an ssh session to a "remote" machine
which runs "cvs up" on an ssd) the display sometimes "freezes". That is:
mouse pointer still moves, but window manager is blocked, all window contents
are frozen.

Switching VTs works, shutting down works cleanly as well.

I am not sure what process I should attach gdb to, any hints welcome.

>How-To-Repeat:

Sniplets from dmesg.boot:

drm: initializing kernel modesetting (CEDAR 0x1002:0x68E0 0x1025:0x0347).
drm: register mmio base: 0xcfee0000
drm: register mmio size: 131072
drm kern info: ATOM BIOS: Acer
radeon0: info: VRAM: 512M 0x0000000000000000 - 0x000000001FFFFFFF (512M used)
radeon0: info: GTT: 1024M 0x0000000020000000 - 0x000000005FFFFFFF
drm: Detected VRAM RAM=200M, BAR=256M
drm: RAM width 64bits DDR
Zone  kernel: Available graphics memory: 1379412 kiB
drm: radeon: 512M of VRAM memory ready
drm: radeon: 1024M of GTT memory ready.
drm: Loading CEDAR Microcode
drm: Internal thermal controller without fan control
drm: radeon: dpm initialized
drm: GART: num cpu pages 262144, num gpu pages 262144
drm: PCIE GART of 1024M enabled (table at 0x000000000025D000).
radeon0: info: WB enabled
radeon0: info: fence driver on ring 0 use gpu addr 0x0000000020000c00 and cpu addr 0x0xffff800046e6ec00
radeon0: info: fence driver on ring 3 use gpu addr 0x0000000020000c0c and cpu addr 0x0xffff800046e6ec0c
radeon0: info: fence driver on ring 5 use gpu addr 0x000000000005c418 and cpu addr 0x0xffff800046a6c418
drm: Supports vblank timestamp caching Rev 2 (21.10.2013).
drm: Driver supports precise vblank timestamp query.
radeon0: info: radeon: using MSI.
radeon0: interrupting at msi3 vec 0 (radeon)
drm: radeon: irq initialized.
drm: ring test on 0 succeeded in 1 usecs
drm: ring test on 3 succeeded in 1 usecs
drm: ring test on 5 succeeded in 1 usecs
drm: UVD initialized successfully.
drm: ib test on ring 0 succeeded in 0 usecs
drm: ib test on ring 3 succeeded in 0 usecs
drm: ib test on ring 5 succeeded
drm: Radeon Display Connectors
drm: Connector 0:
drm:   LVDS-1
drm:   DDC: 0x6560 0x6560 0x6564 0x6564 0x6568 0x6568 0x656c 0x656c
drm:   Encoders:
drm:     LCD1: INTERNAL_UNIPHY
drm: Connector 1:
drm:   HDMI-A-1
drm:   HPD1
drm:   DDC: 0x6440 0x6440 0x6444 0x6444 0x6448 0x6448 0x644c 0x644c
drm:   Encoders:
drm:     DFP1: INTERNAL_UNIPHY1
drm: Connector 2:
drm:   VGA-1
drm:   DDC: 0x6430 0x6430 0x6434 0x6434 0x6438 0x6438 0x643c 0x643c
drm:   Encoders:
drm:     CRT1: INTERNAL_KLDSCP_DAC1
radeondrmkmsfb0 at radeon0
radeon0: info: registered panic notifier
radeondrmkmsfb0: framebuffer at 0xffff800047090000, size 1600x900, depth 32, stride 6400


>Fix:
n/a