[Intel-gfx] [PATCH] drm/i915: Update crtc scaler settings when update_pipe is set

[Hans de Goede]

When the pipe_config's update_pipe flag is set we may need to update the
panel fitting settings. On GEN9+ this means we need to update the crtc's
scaler settings.

This fixes the following WARN_ON, during i915 loading on an Asrock
B150M Pro4S/D3 board with an i5-6500 CPU / graphics:

[drm:pipe_config_err [i915]] *ERROR* mismatch in pch_pfit.enabled
 (expected no, found yes)
pipe state doesn't match!
WARNING: CPU: 3 PID: 305 at drivers/gpu/drm/i915/intel_display.c:12084

With line 12084 being the I915_STATE_WARN call inside the
"if (!intel_pipe_config_compare())" block in verify_crtc_state().

On this board with 2 1920x1080 monitors connected over HDMI the GOP
initializes both monitors at 1920x1080 and despite no scaling being
necessary configures a scaler for one of them.

When booting with fastboot=1 on the initial modeset needs_modeset will
be false while update_pipe is true. Since we were not calling
skl_update_scaler_crtc() in this case we would leave the scaler enabled
causing this error.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 drivers/gpu/drm/i915/intel_display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 62df34d30b1f..df32626e0810 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10919,7 +10919,7 @@ static int intel_crtc_atomic_check(struct drm_crtc *crtc,
 	}
 
 	if (INTEL_GEN(dev_priv) >= 9) {
-		if (mode_changed)
+		if (mode_changed || pipe_config->update_pipe)
 			ret = skl_update_scaler_crtc(pipe_config);
 
 		if (!ret)
-- 
2.20.1