[Intel-gfx] [PATCH] drm/i915: hpd_init needs to be audited for runtime pm

[Daniel Vetter]

On Tue, May 27, 2014 at 11:17 PM, Imre Deak <imre.deak at intel.com> wrote:
> On Tue, 2014-05-27 at 22:58 +0200, Daniel Vetter wrote:
>> Looks like work for Imre or someone else from the runtime pm gang.
>>
>> Cc: Imre Deak <imre.deak at intel.com>
>> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>> ---
>>  drivers/gpu/drm/i915/i915_irq.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
>> index 4ef642348450..4dbdd3b23758 100644
>> --- a/drivers/gpu/drm/i915/i915_irq.c
>> +++ b/drivers/gpu/drm/i915/i915_irq.c
>> @@ -4423,6 +4423,10 @@ void intel_hpd_init(struct drm_device *dev)
>>       unsigned long irqflags;
>>       int i;
>>
>> +     /*
>> +      * AUDIT-ME: This looks unsafe now that we run hpd_init at interesting
>> +      * times due to runtime pm. Same for the connector->polled access below.
>> +      */
>
> Ok, I can go through it, also considering if it's safe to be called from
> other platforms as discussed on IRC. But the above comment seems to
> suggest that we can get here via the runtime PM resume path, which can
> really be called at basically any time (making locking etc an
> interesting problem). But that's not really true in this case, since -
> on VLV at least - we get here only from a well defined point during a
> modeset-on transition.

We actually don't call it anywhere, which is a bit surprising. The
runtime pm irq restore directly calls the low-level functions, but
->hpd_setup isn't called anywhere. I wonder a bit whether hotplug even
works after runtime pm ...

Paulo?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch