[mipsel+rs780e]Occasionally "GPU lockup" after resuming from suspend.

[chenhc at lemote.com]

> On Don, 2011-12-08 at 19:35 +0800, chenhc at lemote.com wrote:
>>
>> I found CP_RB_WPTR has changed when "ring test failed", so I think CP is
>> active, but what it get from ring buffer is wrong.
>
> CP_RB_WPTR is normally only changed by the CPU after adding commands to
> the ring buffer, so I'm afraid that may not be a valid conclusion.
>
>
I'm sorry, I've made a spelling mistake. In fact, CP_RB_RPTR and
CP_RB_WPTR both changed, so I think CP is active.

>> Then, I want to know whether there is a way to check the content that
>> GPU get from ring buffer.
>
> See the r100_debugfs_cp_csq_fifo() function, which generates the output
> for /sys/kernel/debug/dri/0/r100_cp_csq_fifo.
>
Hmmm, I don't think this function can be used by r600 (or write a similar
one for R600), because I haven't found CSQ registers in r600 code.

>
>> BTW, when I use "echo shutdown > /sys/power/disk; echo disk >
>> /sys/power/state" to do a hibernation, there will be occasionally "GPU
>> reset" just like suspend. However, if I use "echo reboot >
>> /sys/power/disk; echo disk > /sys/power/state" to do a hibernation and
>> wakeup automatically, there is no "GPU reset" after hundreds of tests.
>> What does this imply? Power loss cause something break?
>
> Yeah, it sounds like the resume code doesn't properly re-initialize
> something that's preserved on a warm boot but lost on a cold boot.
>
>
> --
> Earthling Michel D