[Intel-gfx] [PATCH 2/3] drm/i915: PSR: Remove Low Power HW tracking mask.

[Paulo Zanoni]

2015-06-30 20:42 GMT-03:00 Rodrigo Vivi <rodrigo.vivi at intel.com>:
> By Spec we should only mask memup and hotplug detection
> for hardware tracking cases. However we always masked
> LPSP because with power well always enabled on audio
> PSR was never being activated and residency was always
> zeroed.
>
> Apparently audio driver is tying power well management
> and runtime PM for some reason. But with audio runtime
> PM working or with audio completely out of picture
> we should remove this mask, otherwise we have a high
> risk of miss screen updates as faced by Matthew.
>
> WARNING: With this patch if snd_intel_hda driver is
> runing and not releasing power well properly PSR will
> constant Exit and Performance Counter will be 0.
>
> But the best thing of this patch is that with one more
> HW tracking working the risks of missed blank screen
> are minimized at most.
>
> This affects just core platforms where PSR exit are also
> helped by HW tracking: Haswell, Broadwell and Skylake
> for now.
>
> v2: Fix commit message explanation. It has nothing to do
> with runtime PM on i915 as previously advertised.

But then, as far as I understood, if you remove the mask, our current
IGT patches will start failing with "PSR disabled" errors, right? So
can you please also provide IGT fixes?

If the only thing we really need is Audio RPM instead of full graphics
RPM, then I suggest you extract igt_setup_audio_runtime_pm() from the
current igt_setup_runtime_pm(), and then call it on the tests that
need PSR.

>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Matthew Garrett <mjg59 at srcf.ucam.org via codon.org.uk>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_psr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
> index d79ba58..cab5153 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -400,7 +400,7 @@ void intel_psr_enable(struct intel_dp *intel_dp)
>
>                 /* Avoid continuous PSR exit by masking memup and hpd */
>                 I915_WRITE(EDP_PSR_DEBUG_CTL(dev), EDP_PSR_DEBUG_MASK_MEMUP |
> -                          EDP_PSR_DEBUG_MASK_HPD | EDP_PSR_DEBUG_MASK_LPSP);
> +                          EDP_PSR_DEBUG_MASK_HPD);
>
>                 /* Enable PSR on the panel */
>                 hsw_psr_enable_sink(intel_dp);
> --
> 2.1.0
>
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-- 
Paulo Zanoni