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

[Manasi Navare]

On Wed, Sep 18, 2019 at 10:51:54AM +0200, Maarten Lankhorst wrote:
> Op 17-09-2019 om 18:37 schreef Manasi Navare:
> > 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 at linux.intel.com>
> >>> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> >>> Cc: Matt Roper <matthew.d.roper at intel.com>
> >>> Cc: Jani Nikula <jani.nikula at intel.com>
> >>> Signed-off-by: Manasi Navare <manasi.d.navare at 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.
> 
> We overwrite func_ctl2 in enable_port_sync so it makes sense to do the same in disable. :)

Yes as per the reviews on the enable patch, the RMW was not recommended, so even here I will just overwrite with ~(PORT_SYNC_MODE_ENABLE | PORT_SYNC_MODE_MASTER_SELECT_MASK);

This sounds good?

Manasi

>