Am 17.03.21 um 16:43 schrieb Maxime Ripard:
> The vc4_set_crtc_possible_masks is meant to run over all the encoders
> and then set their possible_crtcs mask to their associated pixelvalve.
> 
> However, since the commit 39fcb2808376 ("drm/vc4: txp: Turn the TXP into
> a CRTC of its own"), the TXP has been turned to a CRTC and encoder of
> its own, and while it does indeed register an encoder, it no longer has
> an associated pixelvalve. The code will thus run over the TXP encoder
> and set a bogus possible_crtcs mask, overriding the one set in the TXP
> bind function.
> 
> In order to fix this, let's skip any virtual encoder.
> 
> Fixes: 39fcb2808376 ("drm/vc4: txp: Turn the TXP into a CRTC of its own")
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>

dim fixes 39fcb2808376
Fixes: 39fcb2808376 ("drm/vc4: txp: Turn the TXP into a CRTC of its own")
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Eric Anholt <eric@anholt.net>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: <stable@vger.kernel.org> # v5.9+

At least the CC: stable line should be there.

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>

> ---
>   drivers/gpu/drm/vc4/vc4_crtc.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
> index 269390bc586e..f1f2e8cbce79 100644
> --- a/drivers/gpu/drm/vc4/vc4_crtc.c
> +++ b/drivers/gpu/drm/vc4/vc4_crtc.c
> @@ -1018,6 +1018,9 @@ static void vc4_set_crtc_possible_masks(struct drm_device *drm,
>   		struct vc4_encoder *vc4_encoder;
>   		int i;
>   
> +		if (encoder->encoder_type == DRM_MODE_ENCODER_VIRTUAL)
> +			continue;
> +
>   		vc4_encoder = to_vc4_encoder(encoder);
>   		for (i = 0; i < ARRAY_SIZE(pv_data->encoder_types); i++) {
>   			if (vc4_encoder->type == encoder_types[i]) {
> 

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