linux-kernel - Re: [Intel-gfx] [PATCH v5 4/4] drm/i915/gen9_bc: Add W/A for missing STRAP config on TGP PCH + CML combos

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Message-ID: <20210211233035.GA320726@intel.com>
Date:   Thu, 11 Feb 2021 18:30:35 -0500
From:   Rodrigo Vivi <rodrigo.vivi@...el.com>
To:     Lyude Paul <lyude@...hat.com>
Cc:     David Airlie <airlied@...ux.ie>, intel-gfx@...ts.freedesktop.org,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Yijun Shen <Yijun.Shen@...l.com>,
        Dave Airlie <airlied@...hat.com>
Subject: Re: [Intel-gfx] [PATCH v5 4/4] drm/i915/gen9_bc: Add W/A for missing
 STRAP config on TGP PCH + CML combos

On Wed, Feb 10, 2021 at 10:23:58PM -0500, Rodrigo Vivi wrote:
> On Tue, Feb 09, 2021 at 04:28:31PM -0500, Lyude Paul wrote:
> > Apparently the new gen9_bc platforms that Intel has introduced don't
> > provide us with a STRAP config register to read from for initializing DDI
> > B, C, and D detection. So, workaround this by hard-coding our strap config
> > in intel_setup_outputs().
> > 
> > Changes since v4:
> > * Split this into it's own commit
> > 
> > Cc: Matt Roper <matthew.d.roper@...el.com>
> > Cc: Jani Nikula <jani.nikula@...ux.intel.com>
> > Cc: Ville Syrjala <ville.syrjala@...ux.intel.com>
> > [originally from Tejas's work]
> > Signed-off-by: Tejas Upadhyay <tejaskumarx.surendrakumar.upadhyay@...el.com>
> > Signed-off-by: Lyude Paul <lyude@...hat.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index beed08c00b6c..4dee37f8659d 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -11943,7 +11943,14 @@ static void intel_setup_outputs(struct drm_i915_private *dev_priv)
> >  
> >  		/* DDI B, C, D, and F detection is indicated by the SFUSE_STRAP
> >  		 * register */
> > -		found = intel_de_read(dev_priv, SFUSE_STRAP);
> > +		if (HAS_PCH_TGP(dev_priv)) {
> > +			/* W/A due to lack of STRAP config on TGP PCH*/
> > +			found = (SFUSE_STRAP_DDIB_DETECTED |
> > +				 SFUSE_STRAP_DDIC_DETECTED |
> > +				 SFUSE_STRAP_DDID_DETECTED);
> 
> we have somewhere in this function these forced fuse straps for gen9 platform...
> don't we have a ways to combine them?
> 
> Afterall, the reason that we need these forced bits is
> because it is a gen9, not because it is a TGP...

just ignore my non-sense comment... I confused with the 
/* WaIgnoreDDIAStrap: skl */
above...
thought it was for all the ports... not just for port A...

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@...el.com>

> 
> > +		} else {
> > +			found = intel_de_read(dev_priv, SFUSE_STRAP);
> > +		}
> >  
> >  		if (found & SFUSE_STRAP_DDIB_DETECTED)
> >  			intel_ddi_init(dev_priv, PORT_B);
> > -- 
> > 2.29.2
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@...ts.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

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