Op 01-12-16 om 14:13 schreef Ville Syrjälä:
> On Thu, Dec 01, 2016 at 12:56:16PM +0100, Maarten Lankhorst wrote:
>> Op 28-11-16 om 18:37 schreef ville.syrj...@linux.intel.com:
>>> From: Ville Syrjälä <ville.syrj...@linux.intel.com>
>>>
>>> Each DSPARB register can house bits for two separate pipes, hence
>>> we must protect the registers during reprogramming so that parallel
>>> FIFO reconfigurations happening simultaneosly on multiple pipes won't
>>> corrupt each others values.
>>>
>>> Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
>>> ---
>>>  drivers/gpu/drm/i915/i915_drv.c | 1 +
>>>  drivers/gpu/drm/i915/i915_drv.h | 3 +++
>>>  drivers/gpu/drm/i915/intel_pm.c | 6 ++++++
>>>  3 files changed, 10 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/i915/i915_drv.c 
>>> b/drivers/gpu/drm/i915/i915_drv.c
>>> index 0fba4bb5655e..c98032e9112b 100644
>>> --- a/drivers/gpu/drm/i915/i915_drv.c
>>> +++ b/drivers/gpu/drm/i915/i915_drv.c
>>> @@ -811,6 +811,7 @@ static int i915_driver_init_early(struct 
>>> drm_i915_private *dev_priv,
>>>     spin_lock_init(&dev_priv->uncore.lock);
>>>     spin_lock_init(&dev_priv->mm.object_stat_lock);
>>>     spin_lock_init(&dev_priv->mmio_flip_lock);
>>> +   spin_lock_init(&dev_priv->wm.dsparb_lock);
>> Can we make sure all wm updates are done with dev_priv->wm.wm_mutex held 
>> instead?
> We can't grab a mutex from the vblank evade critical section. We'd have
> to hold the mutex across the whole thing then. Not sure if that would be
> a good or a bad thing.
Ah right, I missed that part since it didn't happen in the patches yet, might 
be worth pointing out in the commit message.

Will vlv_wm_values also be updated with that lock in the future? Looks like it 
could be a fun race otherwise.
>> gen9 wm's and ilk wm's use that mutex, for similar reasons.
>>>     mutex_init(&dev_priv->sb_lock);
>>>     mutex_init(&dev_priv->modeset_restore_lock);
>>>     mutex_init(&dev_priv->av_mutex);
>>> diff --git a/drivers/gpu/drm/i915/i915_drv.h 
>>> b/drivers/gpu/drm/i915/i915_drv.h
>>> index 9d808b706824..75439e9a67f7 100644
>>> --- a/drivers/gpu/drm/i915/i915_drv.h
>>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>>> @@ -2169,6 +2169,9 @@ struct drm_i915_private {
>>>     } sagv_status;
>>>  
>>>     struct {
>>> +           /* protects DSPARB registers on pre-g4x/vlv/chv */
>>> +           spinlock_t dsparb_lock;
>>> +
>>>             /*
>>>              * Raw watermark latency values:
>>>              * in 0.1us units for WM0,
>>> diff --git a/drivers/gpu/drm/i915/intel_pm.c 
>>> b/drivers/gpu/drm/i915/intel_pm.c
>>> index 24d85a4e4ed3..9f25f2195a6a 100644
>>> --- a/drivers/gpu/drm/i915/intel_pm.c
>>> +++ b/drivers/gpu/drm/i915/intel_pm.c
>>> @@ -1215,6 +1215,8 @@ static void vlv_pipe_set_fifo_size(struct intel_crtc 
>>> *crtc)
>>>                   pipe_name(crtc->pipe), sprite0_start,
>>>                   sprite1_start, fifo_size);
>>>  
>>> +   spin_lock(&dev_priv->wm.dsparb_lock);
>>> +
>>>     switch (crtc->pipe) {
>>>             uint32_t dsparb, dsparb2, dsparb3;
>>>     case PIPE_A:
>>> @@ -1271,6 +1273,10 @@ static void vlv_pipe_set_fifo_size(struct intel_crtc 
>>> *crtc)
>>>     default:
>>>             break;
>>>     }
>>> +
>>> +   POSTING_READ(DSPARB);
>>> +
>>> +   spin_unlock(&dev_priv->wm.dsparb_lock);
>>>  }
>>>  
>>>  #undef VLV_FIFO


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