Re: [PATCH 4/7] drm/i915: PSR: Mask LPSP hw tracking back again.

From: Daniel Vetter <daniel@ffwll.ch>
To: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: intel-gfx@lists.freedesktop.org, Ivan Mitev <ivan.mitev@gmail.com>
Subject: Re: [PATCH 4/7] drm/i915: PSR: Mask LPSP hw tracking back again.
Date: Wed, 26 Aug 2015 11:11:31 +0200	[thread overview]
Message-ID: <20150826091131.GP20434@phenom.ffwll.local> (raw)
In-Reply-To: <1440118544-26282-4-git-send-email-rodrigo.vivi@intel.com>

On Thu, Aug 20, 2015 at 05:55:41PM -0700, Rodrigo Vivi wrote:
> At the beginning it was masked to allow PSR at all.
> Than it got removed later by my
> commit 09108b90f040 ("drm/i915: PSR: Remove Low Power HW tracking mask.")
> in order to trying fixing one case reported at intel-gfx mailing list
> where we were missing screen updates when runtime_pm was enabled.
> 
> However I verified that other patch that makes flush to force
> invalidate also fixes this issue by itself.
> commit 169de1316c1e ("drm/i915: PSR: Flush means invalidate + flush")
> 
> Mainly now that we are relying more on frontbuffer tracking it is a
> good idea to mask this hw tracking again.
> 
> But besides all this above it is important to hightligh that with LPSP
> unmasked we started seeing some screen freezings as reported at fd.o.
> 
> This patch fixes the unrecoverable frozen screens reported:
> 
> Reference: https://bugs.freedesktop.org/show_bug.cgi?id=91436
> Reference: https://bugs.freedesktop.org/show_bug.cgi?id=91437
> 
> Cc: Ivan Mitev <ivan.mitev@gmail.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Not sure whether you missed it, but did you look into pipe A interrupts
when the screen freezes? Apparently we should try to do manual link
training in that case, and failing to do so with a PSR panel pretty much
fits the description of frozen panel.
-Daniel

> ---
>  drivers/gpu/drm/i915/intel_psr.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
> index 63bbab2..d02d4e2 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -398,9 +398,14 @@ void intel_psr_enable(struct intel_dp *intel_dp)
>  				skl_psr_setup_su_vsc(intel_dp);
>  		}
>  
> -		/* Avoid continuous PSR exit by masking memup and hpd */
> +		/*
> +		 * Per Spec: Avoid continuous PSR exit by masking MEMUP and HPD.
> +		 * Also mask LPSP to avoid dependency on other drivers that
> +		 * might block runtime_pm besides preventing other hw tracking
> +		 * issues now we can rely on frontbuffer tracking.
> +		 */
>  		I915_WRITE(EDP_PSR_DEBUG_CTL(dev), EDP_PSR_DEBUG_MASK_MEMUP |
> -			   EDP_PSR_DEBUG_MASK_HPD);
> +			   EDP_PSR_DEBUG_MASK_HPD | EDP_PSR_DEBUG_MASK_LPSP);
>  
>  		/* Enable PSR on the panel */
>  		hsw_psr_enable_sink(intel_dp);
> -- 
> 2.4.3
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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