[Intel-gfx] [PATCH] drm/i915: Fix PSR2 selective update corruption after PSR1 setup

[Pandiyan, Dhinakaran]

Thanks for checking, appreciate it.

-DK

> -----Original Message-----
> From: Runyan, Arthur J
> Sent: Wednesday, March 20, 2019 11:58 AM
> To: Souza, Jose <jose.souza at intel.com>; Vivi, Rodrigo
> <rodrigo.vivi at intel.com>; Pandiyan, Dhinakaran
> <dhinakaran.pandiyan at intel.com>
> Cc: Aigal, Pavana A <pavana.a.aigal at intel.com>; 'intel-
> gfx at lists.freedesktop.org' <intel-gfx at lists.freedesktop.org>
> Subject: RE: [PATCH] drm/i915: Fix PSR2 selective update corruption after
> PSR1 setup
> 
> PSR2 logic is incorrectly looking at this register bit during DC5 exit.
> Not a DMC problem, but DMC enables DC5.
> I'll update Bspec to require the bit to be not set when PSR2 is used.
> 
> > -----Original Message-----
> > From: Runyan, Arthur J
> > Sent: Tuesday, 12 March, 2019 4:42 PM
> > To: Souza, Jose <jose.souza at intel.com>; Vivi, Rodrigo
> > <rodrigo.vivi at intel.com>; Pandiyan, Dhinakaran
> > <dhinakaran.pandiyan at intel.com>
> > Cc: Aigal, Pavana A <pavana.a.aigal at intel.com>; intel-
> > gfx at lists.freedesktop.org
> > Subject: RE: [PATCH] drm/i915: Fix PSR2 selective update corruption
> > after
> > PSR1 setup
> >
> > Strange.  DMC doesn't look at training patterns.  I've asked the PSR2
> > guys to look for any cross-connection.
> >
> > > -----Original Message-----
> > > From: Souza, Jose
> > > Sent: Tuesday, 12 March, 2019 2:29 PM
> > > To: Vivi, Rodrigo <rodrigo.vivi at intel.com>; Pandiyan, Dhinakaran
> > > <dhinakaran.pandiyan at intel.com>
> > > Cc: Runyan, Arthur J <arthur.j.runyan at intel.com>; Aigal, Pavana A
> > > <pavana.a.aigal at intel.com>; intel-gfx at lists.freedesktop.org
> > > Subject: Re: [PATCH] drm/i915: Fix PSR2 selective update corruption
> > > after
> > > PSR1 setup
> > >
> > > On Tue, 2019-03-12 at 14:14 -0700, Dhinakaran Pandiyan wrote:
> > > > On Tue, 2019-03-12 at 13:53 -0700, Rodrigo Vivi wrote:
> > > > > On Tue, Mar 12, 2019 at 01:42:17PM -0700, José Roberto de Souza
> > > > > wrote:
> > > > > > For some reason if the PSR1 EDP_PSR_TP1_TP3_SEL register is
> > > > > > kept set while PSR2 is enabled, it causes some selective
> > > > > > updates to fail after got back from DC6 for the first time.
> > > >
> > > > That's suspicious, why does a PSR1 control register have any
> > > > effect on PSR2. Was PSR1 enabled before PSR2?
> > >
> > > Yes it only happens when switching from PSR1 -> PSR2, I caught this
> > > issue now because I had a external connector attached so display was
> > > never going to DC6.
> > >
> > > >
> > > >
> > > >
> > > > > > So lets clear this register before enabled PSR2, as it could
> > > > > > be set by a previous i915 module, firmware/BIOS or by a
> > > > > > previous mode that is not compatible with PSR2.
> > > > >
> > > > > Does it happen when you don't have DMC loaded?
> > > > >
> > > > > Because It looks like a DMC bug for me...
> > > > >
> > > > > If by removing DMC we don't see the issue, could we please file
> > > > > this bug to DMC while adding a FIXME with DMC bugged version on it?
> > > > >
> > > > > Aa: Pavana
> > > > >
> > > > > If it doesn't happen with DMC loaded than maybe a HSD would for
> > > > > hw team would be good anyway.
> > > > >
> > > > > Cc: Art.
> > > > >
> > > > > Thanks,
> > > > > Rodrigo.
> > > > >
> > > > > > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> > > > > > Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > > > > > Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> > > > > > ---
> > > > > >  drivers/gpu/drm/i915/intel_psr.c | 12 ++++++++++--
> > > > > >  1 file changed, 10 insertions(+), 2 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/gpu/drm/i915/intel_psr.c
> > > > > > b/drivers/gpu/drm/i915/intel_psr.c
> > > > > > index 7bab6a009e0d..ae62f8124558 100644
> > > > > > --- a/drivers/gpu/drm/i915/intel_psr.c
> > > > > > +++ b/drivers/gpu/drm/i915/intel_psr.c
> > > > > > @@ -494,12 +494,20 @@ static void hsw_activate_psr2(struct
> > > > > > intel_dp
> > > > > > *intel_dp)
> > > > > >  {
> > > > > >  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > > > > >  	u32 val;
> > > > > > +	int idle_frames;
> > > > > > +
> > > > > > +	/*
> > > > > > +	 * Keeping this PSR1 register set while PSR2 is enabled
> > > > > > +causes
> > > > > > some
> > > > > > +	 * PSR2 selective updates to fail, corrupting screen.
> > > > > > +	 */
> > > > > > +	val = I915_READ(EDP_PSR_CTL);
> > > > > > +	if (val & EDP_PSR_TP1_TP3_SEL)
> > > > > > +		I915_WRITE(EDP_PSR_CTL, val &
> > ~EDP_PSR_TP1_TP3_SEL);
> > > >
> > > > Since PSR1 should be disabled at this point, a rmw is not necessary.
> > > > Does this work?
> > > > I915_WRITE(EDP_PSR_CTL, 0);
> > > >
> > > > We could do the same thing in psr_exit() as well.
> > >
> > > Write 0 also works and I'm doing RMW because I always try to save
> > > any writes.
> > >
> > > No need to do it in psr_exit(), the important is do it here because
> > > other i915 module or BIOS could leave it set.
> > >
> > > >
> > > > > >
> > > > > >  	/* Let's use 6 as the minimum to cover all known cases
> > > > > > including the
> > > > > >  	 * off-by-one issue that HW has in some cases.
> > > > > >  	 */
> > > > > > -	int idle_frames = max(6, dev_priv->vbt.psr.idle_frames);
> > > > > > -
> > > > > > +	idle_frames = max(6, dev_priv->vbt.psr.idle_frames);
> > > > > >  	idle_frames = max(idle_frames, dev_priv-
> > >psr.sink_sync_latency
> > > > > > + 1);
> > > > > >  	val = idle_frames << EDP_PSR2_IDLE_FRAME_SHIFT;
> > > > > >
> > > > > > --
> > > > > > 2.21.0
> > > > > >