Am 28.03.22 um 17:36 schrieb 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 <[email protected]>
---
  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);
+

Should be drm_WARN_ON().

Is that something that could be detected during atomic-check steps?

Best regards
Thomas

                        mux = (channel == 2) ? 0 : 1;
                        reg = HVS_READ(SCALER_DISPECTRL);
                        HVS_WRITE(SCALER_DISPECTRL,

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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