Radeon X200M device suspend problem

[Dmitriy Kryuk]

On 12/16/2016 04:01 PM, Michel Dänzer wrote:
> On 16/12/16 01:29 AM, Dmitriy Kryuk wrote:
>> I have a laptop with a Radeon X200M card in it. I use Radeon DRM driver
>> for graphics, and it makes the system hang with display off when trying
>> to suspend (either to disk or to RAM). Using /sys/power/pm_test
>> interface revealed that it freezes when suspending devices.
>>
>> I have tried both Debian repository kernel
>> (https://packages.debian.org/stable/linux-image-3.16.0-4-686-pae) and a
>> custom-built vanilla 3.18.45 kernel with this driver both built-in and
>> included as a module. The problem reproduces the same way. It stops to
>> reproduce if I delete the module radeon.ko or otherwise prevent it from
>> loading. The problem didn't appear before I started using DRM.
...
>> What additional information can I collect and how? What other kernel and
>> driver versions can I try to see if the problem is already solved?
> Please try a current kernel version; ideally 4.9, but definitely much
> newer than 3.18.
>
>
I have built a 4.9 kernel with the configuration based on my 3.18.45 
one, and the behaviour is still the same. How could I get more 
information to debug the problem, at least to make the driver not switch 
off LCD panel power and backlight?