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From: Brian Norris <briannorris@chromium.org>
To: Jani Nikula <jani.nikula@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	linux-kernel@vger.kernel.org,
	Daniel Vetter <daniel.vetter@intel.com>,
	Brian Norris <computersforpeace@gmail.com>,
	Duncan Laurie <dlaurie@chromium.org>
Subject: Re: [RFC PATCH] drm/i915: PSR regressions on Broadwell
Date: Mon, 28 Sep 2015 14:08:01 -0700	[thread overview]
Message-ID: <20150928210801.GA42029@google.com> (raw)
In-Reply-To: <874mifm2wz.fsf@intel.com>

On Mon, Sep 28, 2015 at 10:14:04AM +0300, Jani Nikula wrote:
> On Sat, 26 Sep 2015, Brian Norris <briannorris@chromium.org> wrote:
> > When using PSR, I see the screen freeze after only a few frames (sometimes a
> > split second; sometimes it seems like practically the first frame). Bisecting
> > led me to commit 3301d4092106 ("drm/i915: PSR: Fix DP_PSR_NO_TRAIN_ON_EXIT
> > logic") in v4.2. This patch is the simplest fix that gets it working again for
> > me, but it's probably wrong.
> >
> > Random thought: perhaps my panel's DPCD is programmed incorrectly?
> >
> > Anyway, any tips on fixing this properly?
> 
> Here's a thought:
> 
> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
> index a04b4dc5ed9b..3a911d4a2308 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -274,6 +274,8 @@ static void hsw_psr_enable_source(struct intel_dp *intel_dp)
>  		idle_frames += 4;
>  	}
>  
> +	idle_frames = clamp(idle_frames, 0, 15);
> +
>  	I915_WRITE(EDP_PSR_CTL(dev), val |
>  		   (IS_BROADWELL(dev) ? 0 : link_entry_time) |
>  		   max_sleep_time << EDP_PSR_MAX_SLEEP_TIME_SHIFT |

No dice. The VBT actually gives 0, so I just end up with the default 5 +
4 either way.

> We do clamp the VBT value to range 0..15, but then go on to add to it.

But this patch seems quite reasonable anyway.

Acked-by: Brian Norris <briannorris@chromium.org>

> Otherwise, up to Rodrigo I guess.

Brian
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WARNING: multiple messages have this Message-ID (diff)
From: Brian Norris <briannorris@chromium.org>
To: Jani Nikula <jani.nikula@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	"Brian Norris" <computersforpeace@gmail.com>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	"Stéphane Marchesin" <marcheu@chromium.org>,
	"Duncan Laurie" <dlaurie@chromium.org>
Subject: Re: [RFC PATCH] drm/i915: PSR regressions on Broadwell
Date: Mon, 28 Sep 2015 14:08:01 -0700	[thread overview]
Message-ID: <20150928210801.GA42029@google.com> (raw)
In-Reply-To: <874mifm2wz.fsf@intel.com>

On Mon, Sep 28, 2015 at 10:14:04AM +0300, Jani Nikula wrote:
> On Sat, 26 Sep 2015, Brian Norris <briannorris@chromium.org> wrote:
> > When using PSR, I see the screen freeze after only a few frames (sometimes a
> > split second; sometimes it seems like practically the first frame). Bisecting
> > led me to commit 3301d4092106 ("drm/i915: PSR: Fix DP_PSR_NO_TRAIN_ON_EXIT
> > logic") in v4.2. This patch is the simplest fix that gets it working again for
> > me, but it's probably wrong.
> >
> > Random thought: perhaps my panel's DPCD is programmed incorrectly?
> >
> > Anyway, any tips on fixing this properly?
> 
> Here's a thought:
> 
> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
> index a04b4dc5ed9b..3a911d4a2308 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -274,6 +274,8 @@ static void hsw_psr_enable_source(struct intel_dp *intel_dp)
>  		idle_frames += 4;
>  	}
>  
> +	idle_frames = clamp(idle_frames, 0, 15);
> +
>  	I915_WRITE(EDP_PSR_CTL(dev), val |
>  		   (IS_BROADWELL(dev) ? 0 : link_entry_time) |
>  		   max_sleep_time << EDP_PSR_MAX_SLEEP_TIME_SHIFT |

No dice. The VBT actually gives 0, so I just end up with the default 5 +
4 either way.

> We do clamp the VBT value to range 0..15, but then go on to add to it.

But this patch seems quite reasonable anyway.

Acked-by: Brian Norris <briannorris@chromium.org>

> Otherwise, up to Rodrigo I guess.

Brian

  reply	other threads:[~2015-09-28 21:08 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-26  2:26 [RFC PATCH] drm/i915: PSR regressions on Broadwell Brian Norris
2015-09-26  2:26 ` Brian Norris
2015-09-28  7:14 ` Jani Nikula
2015-09-28  7:14   ` Jani Nikula
2015-09-28 21:08   ` Brian Norris [this message]
2015-09-28 21:08     ` Brian Norris

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