drm/i915/display: Do not write in removed FBC fence registers

Platforms without fences don't have FBC host tracking and those
registers are marked as reserved in those platforms.

v2: checking num_fences to write to FBC fence registers (Ville)

Cc: Rodrigo Vivi <[email protected]>
Cc: Matt Roper <[email protected]>
Cc: Dhinakaran Pandiyan <[email protected]>
Cc: Ville Syrjälä <[email protected]>
Reviewed-by: Ville Syrjälä <[email protected]>
Signed-off-by: Radhakrishna Sripada <[email protected]>
Signed-off-by: Lucas De Marchi <[email protected]>
Signed-off-by: José Roberto de Souza <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 010b1107671fa4398300d992cec55c956b433a86..2e5d835a9eaa866e0a6c8c94b35ff00cbcf04db7 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -321,7 +321,7 @@ static void gen7_fbc_activate(struct drm_i915_private *dev_priv)
                               SNB_CPU_FENCE_ENABLE | params->fence_id);
                intel_de_write(dev_priv, DPFC_CPU_FENCE_OFFSET,
                               params->crtc.fence_y_offset);
-       } else {
+       } else if (dev_priv->ggtt.num_fences) {
                intel_de_write(dev_priv, SNB_DPFC_CTL_SA, 0);
                intel_de_write(dev_priv, DPFC_CPU_FENCE_OFFSET, 0);
        }