[PATCH 5/6] drm/vc4: kms: Warn if we have an incompatible muxing setup

[Maxime Ripard]

The documentation explicitly states we must prevent the output
2 and 3 from feeding from the same HVS channel.

Let's add a warning to make some noise if we ever find ourselves in such
a case.

Signed-off-by: Maxime Ripard <maxime at cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_kms.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 94c58ec37a27..d94f78eac936 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -286,6 +286,9 @@ static void vc5_hvs_pv_muxing_commit(struct vc4_dev *vc4,
 
 		switch (vc4_crtc->data->hvs_output) {
 		case 2:
+			WARN_ON(VC4_GET_FIELD(HVS_READ(SCALER_DISPCTRL),
+					      SCALER_DISPCTRL_DSP3_MUX) == channel);
+
 			mux = (channel == 2) ? 0 : 1;
 			reg = HVS_READ(SCALER_DISPECTRL);
 			HVS_WRITE(SCALER_DISPECTRL,
-- 
2.35.1