Re: [PATCH 5/6] drm/i915/display/icl: Disable transcoder port sync as part of crtc_disable() sequence

From: Manasi Navare <manasi.d.navare@intel.com>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 5/6] drm/i915/display/icl: Disable transcoder port sync as part of crtc_disable() sequence
Date: Tue, 17 Sep 2019 09:37:07 -0700	[thread overview]
Message-ID: <20190917163707.GA29180@intel.com> (raw)
In-Reply-To: <156576de-c2a0-bbdc-7434-209df041e97c@linux.intel.com>

On Tue, Sep 17, 2019 at 05:04:28PM +0200, Maarten Lankhorst wrote:
> Op 09-09-2019 om 05:43 schreef Manasi Navare:
> > This clears the transcoder port sync bits of the TRANS_DDI_FUNC_CTL2
> > register during crtc_disable().
> >
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Matt Roper <matthew.d.roper@intel.com>
> > Cc: Jani Nikula <jani.nikula@intel.com>
> > Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 23 ++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index 351c90ad7059..07deb0b93f5c 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -4438,6 +4438,26 @@ static void icl_enable_trans_port_sync(const struct intel_crtc_state *crtc_state
> >  		   trans_ddi_func_ctl2_val);
> >  }
> >  
> > +static void icl_disable_transcoder_port_sync(const struct intel_crtc_state *old_crtc_state)
> > +{
> > +	struct intel_crtc *crtc = to_intel_crtc(old_crtc_state->base.crtc);
> > +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> > +	i915_reg_t reg;
> > +	u32 trans_ddi_func_ctl2_val;
> > +
> > +	if (old_crtc_state->master_transcoder == INVALID_TRANSCODER)
> > +		return;
> > +
> > +	DRM_DEBUG_KMS("Disabling Transcoder Port Sync on Slave Transcoder %s\n",
> > +		      transcoder_name(old_crtc_state->cpu_transcoder));
> > +
> > +	reg = TRANS_DDI_FUNC_CTL2(old_crtc_state->cpu_transcoder);
> > +	trans_ddi_func_ctl2_val = I915_READ(reg);
> > +	trans_ddi_func_ctl2_val &= ~(PORT_SYNC_MODE_ENABLE |
> > +				     PORT_SYNC_MODE_MASTER_SELECT_MASK);
> > +	I915_WRITE(reg, trans_ddi_func_ctl2_val);
> > +}
> > +
> Would anything break if we just wrote 0 here?

We dont want to accidently reset other bits in the register which are for DSI and not used currently but
to make this function more future proof, I have avoided writing a 0

But if you strongly feel against this, I can switch this to writing 0 directly.

Manasi

> >  static void intel_update_pipe_config(const struct intel_crtc_state *old_crtc_state,
> >  				     const struct intel_crtc_state *new_crtc_state)
> >  {
> > @@ -6687,6 +6707,9 @@ static void haswell_crtc_disable(struct intel_crtc_state *old_crtc_state,
> >  	if (intel_crtc_has_type(old_crtc_state, INTEL_OUTPUT_DP_MST))
> >  		intel_ddi_set_vc_payload_alloc(old_crtc_state, false);
> >  
> > +	if (INTEL_GEN(dev_priv) >= 11)
> > +		icl_disable_transcoder_port_sync(old_crtc_state);
> > +
> >  	if (!transcoder_is_dsi(cpu_transcoder))
> >  		intel_ddi_disable_transcoder_func(old_crtc_state);
> >  
> 
> 
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