[Intel-gfx] [PATCH 3/3] drm/i915/dp: Disable Port sync mode correctly on teardown

[Ville Syrjälä]

On Wed, Dec 11, 2019 at 01:14:25PM -0800, Manasi Navare wrote:
> While clearing the Ports ync mode enable and master select bits
> we need to make sure that we perform a RMW for disable else
> it sets the other bits casuing unwanted sideeffects.
> 
> Bugzilla: https://gitlab.freedesktop.org/drm/intel/issues/5
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Fixes: 51528afe7c5e ("drm/i915/display/icl: Disable transcoder port sync as part of crtc_disable() sequence")
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index c0a2dab3fe67..3fccda0f1f36 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -4599,7 +4599,8 @@ static void icl_disable_transcoder_port_sync(const struct intel_crtc_state *old_
>  		      transcoder_name(old_crtc_state->cpu_transcoder));
>  
>  	reg = TRANS_DDI_FUNC_CTL2(old_crtc_state->cpu_transcoder);
> -	trans_ddi_func_ctl2_val = ~(PORT_SYNC_MODE_ENABLE |
> +	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);

I915_WRITE(TRANS_DDI_FUNC_CTL2, 0);

>  }
> -- 
> 2.19.1

-- 
Ville Syrjälä
Intel