[Intel-gfx] [PATCH] drm/i915: run intel_uncore_early_sanitize earlier on resume

[Paulo Zanoni]

2014-10-10 8:25 GMT-03:00 Imre Deak <imre.deak at intel.com>:
> On Thu, 2014-10-09 at 14:46 -0300, Paulo Zanoni wrote:
>> From: Paulo Zanoni <paulo.r.zanoni at intel.com>
>>
>> As far as I understand, intel_uncore_early_sanitize() was supposed to
>> be ran before any register access, but currently
>> intel_resume_prepare() is ran earlier, and it does register
>> access. I don't think it should be safe to be calling
>> I915_{READ,WRITE} without calling intel_uncore_early_sanitize() first.
>>
>> One of the problems we currently have is that when we suspend/resume
>> BDW, the FPGA_DBG_RM_NOCLAIM bit becomes 1, so we end up printing an
>> "unclaimed register" message on resume, but this message doesn't
>> really seem to have been triggered by our driver or user space, since
>> the bit was not there before suspending, and gets there just after
>> resuming, before any of our own register accesses. So calling
>> intel_uncore_early_sanitize() as a first thing will allow us to stop
>> printing the error message, fixing the "bug".
>
> One issue is that intel_uncore_early_sanitize() uses forcewake, which is
> enabled only in prepare resume for VLV (vlv_allow_gt_wake()). Maybe
> FPGA_DBG could be reset separately before the rest?

It doesn't "use" forcewake, it calls intel_uncore_forcewake_reset().
Shouldn't we move the vlv code (e.g., vlv_allow_gt_wake()) to inside
intel_uncore_forcewake_reset() instead?

To my understanding, it doesn't make sense to call anything at all
before intel_uncore_early_sanitize()...

>
>>
>> Cc: Chris Wilson <chris at chris-wilson.co.uk>
>> Cc: Imre Deak <imre.deak at intel.com>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83094
>> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_drv.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Maybe we need to move even more code up?
>>
>> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
>> index a05a1d0..dffb173 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.c
>> +++ b/drivers/gpu/drm/i915/i915_drv.c
>> @@ -665,11 +665,11 @@ static int i915_drm_thaw_early(struct drm_device *dev)
>>       struct drm_i915_private *dev_priv = dev->dev_private;
>>       int ret;
>>
>> +     intel_uncore_early_sanitize(dev, true);
>>       ret = intel_resume_prepare(dev_priv, false);
>>       if (ret)
>>               DRM_ERROR("Resume prepare failed: %d,Continuing resume\n", ret);
>>
>> -     intel_uncore_early_sanitize(dev, true);
>>       intel_uncore_sanitize(dev);
>>       intel_power_domains_init_hw(dev_priv);
>>
>
>



-- 
Paulo Zanoni