[PATCH] media: mali-c55: Ignore disconnected queues when checking readiness

[PATCH] media: mali-c55: Ignore disconnected queues when checking readiness

[Linus Walleij]

mali_c55_pipeline_ready() waits for every video queue to enter its
start_streaming callback, regardless of whether its media link is enabled.

When libcamera uses the TPG, it disables the statistics and parameters
links and queues only image buffers. Although STREAMON succeeds on the
metadata nodes, videobuf2 never invokes their callbacks without queued
buffers. The ISP and TPG are therefore never enabled and capture hangs.

An unused full-resolution or downscaled output can similarly prevent the
pipeline from starting.

Only require queues connected through enabled media links to have started.

Use media_pad_remote_pad_first() to check the video node pads, retaining
the capability check before accessing the optional downscale device.

The shared readiness check also keeps stream-off consistent: the first
active queue to stop disables the ISP.

Fixes: d5f281f3dd29 ("media: mali-c55: Add Mali-C55 ISP driver")
Assisted-by: LLM
Signed-off-by: Linus Walleij <linusw@kernel.org>
---
Wait only for video queues connected by enabled media links. This allows
TPG capture without metadata buffers and capture through a single output.

Tested on the Renesas RZ/V2H:

root@localhost:~# cam -c 1 --capture=32
INFO Camera camera_manager.cpp:340 libcamera v0.7.2+152-0024628d
INFO Camera camera_manager.cpp:223 Adding camera 'mali-c55 tpg' for
     pipeline handler mali-c55
WARN MaliC55 mali-c55.cpp:1878 Unable to find CRU for memory input
Using camera mali-c55 tpg as cam0
INFO Camera camera.cpp:1216 configuring streams: (0) 1920x1080-RGB565/Unset
cam0: Capture 32 frames
30.914700 (0.00 fps) cam0-stream0 seq: 000000 bytesused: 4147200
31.132789 (4.59 fps) cam0-stream0 seq: 000001 bytesused: 4147200
31.241978 (9.16 fps) cam0-stream0 seq: 000002 bytesused: 4147200
31.351047 (9.17 fps) cam0-stream0 seq: 000003 bytesused: 4147200
(...)

Also tested with camshark, but only solid black test pattern works,
because of something random:
to_bgr888 failed: No backend could handle RGB565 with given options
---
 drivers/media/platform/arm/mali-c55/mali-c55-core.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-core.c b/drivers/media/platform/arm/mali-c55/mali-c55-core.c
index f28e9f4354ac..ab2ad51c9e0b 100644
--- a/drivers/media/platform/arm/mali-c55/mali-c55-core.c
+++ b/drivers/media/platform/arm/mali-c55/mali-c55-core.c
@@ -510,11 +510,16 @@ bool mali_c55_pipeline_ready(struct mali_c55 *mali_c55)
 	struct mali_c55_params *params = &mali_c55->params;
 	struct mali_c55_stats *stats = &mali_c55->stats;
 
-	return vb2_start_streaming_called(&fr->queue) &&
+	/* Only wait for queues connected through enabled media links. */
+	return (!media_pad_remote_pad_first(&fr->pad) ||
+		vb2_start_streaming_called(&fr->queue)) &&
 	       (!(mali_c55->capabilities & MALI_C55_GPS_DS_PIPE_FITTED) ||
+		!media_pad_remote_pad_first(&ds->pad) ||
 		vb2_start_streaming_called(&ds->queue)) &&
-	       vb2_start_streaming_called(&params->queue) &&
-	       vb2_start_streaming_called(&stats->queue);
+	       (!media_pad_remote_pad_first(&params->pad) ||
+		vb2_start_streaming_called(&params->queue)) &&
+	       (!media_pad_remote_pad_first(&stats->pad) ||
+		vb2_start_streaming_called(&stats->queue));
 }
 
 static int mali_c55_check_hwcfg(struct mali_c55 *mali_c55)

---
base-commit: 5316e507dc6ffa668122d000ac83e2daf2a2a865
change-id: 20260923-mali-c55-tpg-capture-be029caacc1e

Best regards,
--  
Linus Walleij <linusw@kernel.org>

Re: [PATCH] media: mali-c55: Ignore disconnected queues when checking readiness

[Jacopo Mondi]

Hi Linus

On Wed, Sep 23, 2026 at 11:10:33PM +0200, Linus Walleij wrote:
> mali_c55_pipeline_ready() waits for every video queue to enter its
> start_streaming callback, regardless of whether its media link is enabled.
>
> When libcamera uses the TPG, it disables the statistics and parameters
> links and queues only image buffers. Although STREAMON succeeds on the
> metadata nodes, videobuf2 never invokes their callbacks without queued
> buffers. The ISP and TPG are therefore never enabled and capture hangs.
>
> An unused full-resolution or downscaled output can similarly prevent the
> pipeline from starting.
>
> Only require queues connected through enabled media links to have started.
>
> Use media_pad_remote_pad_first() to check the video node pads, retaining
> the capability check before accessing the optional downscale device.
>
> The shared readiness check also keeps stream-off consistent: the first
> active queue to stop disables the ISP.
>
> Fixes: d5f281f3dd29 ("media: mali-c55: Add Mali-C55 ISP driver")
> Assisted-by: LLM
> Signed-off-by: Linus Walleij <linusw@kernel.org>
> ---
> Wait only for video queues connected by enabled media links. This allows
> TPG capture without metadata buffers and capture through a single output.

Oh great, TPG was broken since a long time now

>
> Tested on the Renesas RZ/V2H:
>
> root@localhost:~# cam -c 1 --capture=32
> INFO Camera camera_manager.cpp:340 libcamera v0.7.2+152-0024628d
> INFO Camera camera_manager.cpp:223 Adding camera 'mali-c55 tpg' for
>      pipeline handler mali-c55
> WARN MaliC55 mali-c55.cpp:1878 Unable to find CRU for memory input
> Using camera mali-c55 tpg as cam0
> INFO Camera camera.cpp:1216 configuring streams: (0) 1920x1080-RGB565/Unset
> cam0: Capture 32 frames
> 30.914700 (0.00 fps) cam0-stream0 seq: 000000 bytesused: 4147200
> 31.132789 (4.59 fps) cam0-stream0 seq: 000001 bytesused: 4147200
> 31.241978 (9.16 fps) cam0-stream0 seq: 000002 bytesused: 4147200
> 31.351047 (9.17 fps) cam0-stream0 seq: 000003 bytesused: 4147200
> (...)
>
> Also tested with camshark, but only solid black test pattern works,
> because of something random:
> to_bgr888 failed: No backend could handle RGB565 with given options
> ---
>  drivers/media/platform/arm/mali-c55/mali-c55-core.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-core.c b/drivers/media/platform/arm/mali-c55/mali-c55-core.c
> index f28e9f4354ac..ab2ad51c9e0b 100644
> --- a/drivers/media/platform/arm/mali-c55/mali-c55-core.c
> +++ b/drivers/media/platform/arm/mali-c55/mali-c55-core.c
> @@ -510,11 +510,16 @@ bool mali_c55_pipeline_ready(struct mali_c55 *mali_c55)
>  	struct mali_c55_params *params = &mali_c55->params;
>  	struct mali_c55_stats *stats = &mali_c55->stats;
>
> -	return vb2_start_streaming_called(&fr->queue) &&
> +	/* Only wait for queues connected through enabled media links. */
> +	return (!media_pad_remote_pad_first(&fr->pad) ||
> +		vb2_start_streaming_called(&fr->queue)) &&
>  	       (!(mali_c55->capabilities & MALI_C55_GPS_DS_PIPE_FITTED) ||
> +		!media_pad_remote_pad_first(&ds->pad) ||
>  		vb2_start_streaming_called(&ds->queue)) &&
> -	       vb2_start_streaming_called(&params->queue) &&
> -	       vb2_start_streaming_called(&stats->queue);
> +	       (!media_pad_remote_pad_first(&params->pad) ||
> +		vb2_start_streaming_called(&params->queue)) &&
> +	       (!media_pad_remote_pad_first(&stats->pad) ||
> +		vb2_start_streaming_called(&stats->queue));

Using media_pad_remote_pad_first() might sound a bit count-intuitive
to check if a link is enabled, but it works indeed and I found no
other easy way to check for this.

Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

Thanks
  j

>  }
>
>  static int mali_c55_check_hwcfg(struct mali_c55 *mali_c55)
>
> ---
> base-commit: 5316e507dc6ffa668122d000ac83e2daf2a2a865
> change-id: 20260923-mali-c55-tpg-capture-be029caacc1e
>
> Best regards,
> --
> Linus Walleij <linusw@kernel.org>
>