[Intel-gfx] [PATCH 1/5] drm/i915: Cleanup instdone state

[Ben Widawsky]

On 2012-08-15 02:14, Chris Wilson wrote:
> On Tue, 14 Aug 2012 14:35:13 -0700, Ben Widawsky <ben at bwidawsk.net> 
> wrote:
>> Clear the cached instdone state to match what we expect from 
>> hardware
>> and prevent us from comparing stale values.
>>
>> Actually, clearing the state is not the same as setting idle state.
>> There would be a known state of idle (ie. all units are done), but 
>> since
>> it differs for every platform, we can just set 0, and let the 
>> hangcheck
>> progress as normal.
>>
>> By putting the clear into add_request we are essentially 
>> initializing
>> the cached instdone to a known state before we start the hangcheck
>> timer.
>>
>> v2: clear instdone in more place (Chris)
>> Rewrote the commit message
>>
>> References: https://bugs.freedesktop.org/show_bug.cgi?id=52429
>> Tested-by: Guang A Yang <guang.a.yang at intel.com>
>> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
>
> So if hangcheck is already running and we add a new request, we still
> clear the "stale" state. This means that we may take an extra tick 
> after
> a new request for hangcheck to raise an error. Not a big deal and it
> keeps the code clean. Though possibly deserves a comment?
>
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> -Chris

I was thinking about this exactly. I rationalized it as comparing stale 
state and comparing 0 state should result in the same number of retries, 
unless of course stale state happens to be equal to the state at the 
first timeout. This thinking led me to start thinking that this patch 
wasn't even really necessary at all, so I started going lalala.

-- 
Ben Widawsky, Intel Open Source Technology Center