Re: [Intel-gfx] [PATCH 5/5] drm/i915/psr: Wait for PSR transition to complete before exiting.

[Pandiyan, Dhinakaran]

On Fri, 2018-02-16 at 08:58 +, Chris Wilson wrote:
> Quoting Dhinakaran Pandiyan (2018-02-16 04:33:22)
> > With fbdev, screen freezes after a few continuous PSR exit->enter cycles.
> > Printing out the PSR status register clearly showed this freeze coincided
> > with exiting when the hardware is in a transitory state. So wait for a max
> > of 100 ms (~6 frames) for PSR to become active and then exit.
> > 
> > Cc: Rodrigo Vivi 
> > Signed-off-by: Dhinakaran Pandiyan 
> > ---
> >  drivers/gpu/drm/i915/intel_psr.c | 11 +++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_psr.c 
> > b/drivers/gpu/drm/i915/intel_psr.c
> > index 2a31c7cbdb41..d6669f5f890f 100644
> > --- a/drivers/gpu/drm/i915/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/intel_psr.c
> > @@ -738,6 +738,17 @@ static void intel_psr_exit(struct drm_i915_private 
> > *dev_priv)
> > WARN_ON(!(val & EDP_PSR2_ENABLE));
> > I915_WRITE(EDP_PSR2_CTL, val & ~EDP_PSR2_ENABLE);
> > } else {
> > +   /* Wait for about 6 frames in case we just enabled 
> > PSR,
> > +* this prevents the screen from freezing as the HW 
> > does
> > +* not seem to be able to back off cleanly it is 
> > already
> > +* trying to enter PSR.
> > +*/
> > +   intel_wait_for_register(dev_priv,
> > +   EDP_PSR_STATUS,
> > +   EDP_PSR_STATUS_STATE_MASK,
> > +   EDP_PSR_STATUS_STATE_SRDENT,
> > +   100);
> 
> I'm going to suggest that you want a DRM_DEBUG_KMS() (_DRIVER? Not sure
> what works best for PSR/frontbuffer-tracking) at least for spotting
> trouble when it times out. I would start with a DRM_ERROR for a few CI
> passes just to see what's happening on our machines before toning it
> down for production.

Thanks for the suggestion, makes sense. I don't think we have a test to
emulate a blinking fbcon cursor, which happens to trigger continuous PSR
flushes. I'll look into it.


-DK


> -Chris
> ___
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
___
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

Re: [Intel-gfx] [PATCH 5/5] drm/i915/psr: Wait for PSR transition to complete before exiting.

[Chris Wilson]

Quoting Dhinakaran Pandiyan (2018-02-16 04:33:22)
> With fbdev, screen freezes after a few continuous PSR exit->enter cycles.
> Printing out the PSR status register clearly showed this freeze coincided
> with exiting when the hardware is in a transitory state. So wait for a max
> of 100 ms (~6 frames) for PSR to become active and then exit.
> 
> Cc: Rodrigo Vivi 
> Signed-off-by: Dhinakaran Pandiyan 
> ---
>  drivers/gpu/drm/i915/intel_psr.c | 11 +++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_psr.c 
> b/drivers/gpu/drm/i915/intel_psr.c
> index 2a31c7cbdb41..d6669f5f890f 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -738,6 +738,17 @@ static void intel_psr_exit(struct drm_i915_private 
> *dev_priv)
> WARN_ON(!(val & EDP_PSR2_ENABLE));
> I915_WRITE(EDP_PSR2_CTL, val & ~EDP_PSR2_ENABLE);
> } else {
> +   /* Wait for about 6 frames in case we just enabled 
> PSR,
> +* this prevents the screen from freezing as the HW 
> does
> +* not seem to be able to back off cleanly it is 
> already
> +* trying to enter PSR.
> +*/
> +   intel_wait_for_register(dev_priv,
> +   EDP_PSR_STATUS,
> +   EDP_PSR_STATUS_STATE_MASK,
> +   EDP_PSR_STATUS_STATE_SRDENT,
> +   100);

I'm going to suggest that you want a DRM_DEBUG_KMS() (_DRIVER? Not sure
what works best for PSR/frontbuffer-tracking) at least for spotting
trouble when it times out. I would start with a DRM_ERROR for a few CI
passes just to see what's happening on our machines before toning it
down for production.
-Chris
___
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx