KMS and Radeon RS880 (HD 4200)

Jerome Glisse glisse at
Wed Jul 14 16:19:46 PDT 2010

On 07/14/2010 07:02 PM, Godfrey Benitez wrote:
> On Wed, 7/14/10, alexdeucher wrote:
>> On Wed, Jul 14, 2010 at 8:29 AM, xlistmail wrote:
>>> I have an AMD 785G-based motherboard with built-in Radeon
>>> graphics identified by lspci as "ATI Technologies Inc RS880
>>> [Radeon HD 4200]". I can easily get month-long uptimes
>>> when Kernel Mode Setting is disabled. However, when KMS
>>> is enabled, the screen locks within two days of running
>>> continuously, sometime even less. By lock, I mean the monitor
>>> turns black. The keyboard still appears responsive, I can
>>> toggle Num Lock and Caps Lock on and off,  and I can issue
>>> Ctrl-Alt-Delete to reboot the computer.
>>> The bug appears to be randomly triggered. It has happened
>>> while I am running widely different programs like Firefox
>>> and Abiword. (Surprisingly, the bug has yet to happen
>>> when I'm playing a presumably graphics-intensive 3D game
>>> like Glest). Interestingly, however, the bug happens more
>>> frequently (it happens faster) when I choose to reboot the
>>> computer (hot restart) rather than shut it down and then
>>> turn it back on (cold start).
>>> The kernel log (kern.log) shows a string of error messages
>>> that begins (trimmed to avoid spamming the list):
>> That's a GPU lockup.  Unfortunately, unless you have a reliable test
>> case, it's very hard to track down the cause.
>>> Jul 14 16:45:19 localhost kernel: [121762.072083] [drm:radeon_fence_wait]
>>> *ERROR* fence(ffff880076f71a40:0x0130ECFB) 504ms timeout going to reset GPU
>>> Jul 14 16:45:19 localhost kernel: [121762.072096] radeon 0000:01:05.0: GPU
>>> softreset
>>> Jul 14 16:45:19 localhost kernel: [121762.072101] radeon 0000:01:05.0:
>>> R_008010_GRBM_STATUS=0xA27334AC
> [etc]
> Thanks for the reply. I was just hoping there was some other magic
> option I could pass to modprobe besides "radeon modeset=(0|1)"?
> modinfo gives several other options for the radeon module, omitting
> the obviously nonrelevant ones like benchmark, tv and testing:
> no_wb:Disable AGP writeback for scratch registers (int)
> dynclks:Disable/Enable dynamic clocks (int)
> r4xx_atom:Enable ATOMBIOS modesetting for R4xx (int)
> vramlimit:Restrict VRAM for testing (int)
> agpmode:AGP Mode (-1 == PCI) (int)
> gartsize:Size of PCIE/IGP gart to setup in megabytes (32,64, etc)
> connector_table:Force connector table (int)
> new_pll:Select new PLL code for AVIVO chips (int)
> Also, while I'm running without KMS at the moment, I remember seeing a BIOS
> warning when I restarted my system after the X freeze. If I recall correctly
> it mentioned something about a "sync flood". My IGP is using a combination
> of UMA plus sideport memory (with no option to run on Sideport alone.)
> Is there a difference in the way the kernel handles modesetting so that
> user mode doesn't crash?

User mode is also subject to same kind of lockup. Some GPU/configuration
are more sensitive under KMS, others are more sensitive under UMS.


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