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

[Maarten Lankhorst]

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. :)