Re: [Intel-gfx] [PATCH] drm/i915/dp: DP PHY compliance for JSL

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: "Almahallawy, Khaled" <khaled.almahallawy@intel.com>
Cc: "intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"Srinivas, Vidya" <vidya.srinivas@intel.com>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>
Subject: Re: [Intel-gfx] [PATCH] drm/i915/dp: DP PHY compliance for JSL
Date: Fri, 5 Jun 2020 00:03:19 +0300	[thread overview]
Message-ID: <20200604210319.GJ6112@intel.com> (raw)
In-Reply-To: <fea323968324ceefe813d34d80fdd9779614aa01.camel@intel.com>

On Thu, Jun 04, 2020 at 08:01:03PM +0000, Almahallawy, Khaled wrote:
> On Thu, 2020-06-04 at 22:06 +0300, Ville Syrjälä wrote:
> > On Thu, Jun 04, 2020 at 10:33:48AM +0530, Vidya Srinivas wrote:
> > > Signed-off-by: Khaled Almahallawy <khaled.almahallawy@intel.com>
> > > Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_dp.c | 40
> > > ++++++++++++++++++++++++++-------
> > >  1 file changed, 32 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > > b/drivers/gpu/drm/i915/display/intel_dp.c
> > > index 7223367171d1..44663e8ac9a1 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > > @@ -5470,22 +5470,32 @@ intel_dp_autotest_phy_ddi_disable(struct
> > > intel_dp *intel_dp)
> > >  	struct drm_i915_private *dev_priv = to_i915(dev);
> > >  	struct intel_crtc *crtc = to_intel_crtc(intel_dig_port-
> > > >base.base.crtc);
> > >  	enum pipe pipe = crtc->pipe;
> > > -	u32 trans_ddi_func_ctl_value, trans_conf_value,
> > > dp_tp_ctl_value;
> > > +	u32 trans_ddi_func_ctl_value, trans_conf_value,
> > > dp_tp_ctl_value, trans_ddi_port_mask;
> > > +	enum port port = intel_dig_port->base.port;
> > > +	i915_reg_t dp_tp_reg;
> > > +
> > > +	if (IS_ELKHARTLAKE(dev_priv)) {
> > > +		dp_tp_reg = DP_TP_CTL(port);
> > > +		trans_ddi_port_mask = TRANS_DDI_PORT_MASK;
> > > +	} else if (IS_TIGERLAKE(dev_priv)) {
> > > +		dp_tp_reg = TGL_DP_TP_CTL(pipe);
> > > +		trans_ddi_port_mask = TGL_TRANS_DDI_PORT_MASK;
> > > +	}
> > >  
> > >  	trans_ddi_func_ctl_value = intel_de_read(dev_priv,
> > >  						 TRANS_DDI_FUNC_CTL(pip
> > > e));
> > >  	trans_conf_value = intel_de_read(dev_priv, PIPECONF(pipe));
> > > -	dp_tp_ctl_value = intel_de_read(dev_priv, TGL_DP_TP_CTL(pipe));
> > >  
> > > +	dp_tp_ctl_value = intel_de_read(dev_priv, dp_tp_reg);
> > >  	trans_ddi_func_ctl_value &= ~(TRANS_DDI_FUNC_ENABLE |
> > > -				      TGL_TRANS_DDI_PORT_MASK);
> > > +					trans_ddi_port_mask);
> > >  	trans_conf_value &= ~PIPECONF_ENABLE;
> > >  	dp_tp_ctl_value &= ~DP_TP_CTL_ENABLE;
> > >  
> > >  	intel_de_write(dev_priv, PIPECONF(pipe), trans_conf_value);
> > >  	intel_de_write(dev_priv, TRANS_DDI_FUNC_CTL(pipe),
> > >  		       trans_ddi_func_ctl_value);
> > > -	intel_de_write(dev_priv, TGL_DP_TP_CTL(pipe), dp_tp_ctl_value);
> > > +	intel_de_write(dev_priv, dp_tp_reg, dp_tp_ctl_value);
> > 
> > All this ad-hoc modeset code really should not exist. It's going to
> > have different bugs than the norma modeset paths, so compliance
> > testing
> > this special code proves absolutely nothing about the normal modeset
> > code. IMO someone needs to take up the task of rewrtiting all this to
> > just perform normal modesets.
> 
> Agree. I've just found that we get kernel NULL pointer dereference and
> panic when we try to access to_intel_crtc(intel_dig_port-
> >base.base.crtc).

Yeah, that's a legacy pointer which should no longer be used at all
with atomic drivers. I'm slowly trying to clear out all this legacy
cruft. The next step I had hoped to take was
https://patchwork.freedesktop.org/series/76993/ but then this
compliacnce stuff landed and threw another wrench into the works.

-- 
Ville Syrjälä
Intel
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