linux-kernel - Re: [PATCH] media: mali-c55: Fix NULL dev stream alert for tpg sub-device

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Message-ID: <aWYHPKMVFu_QC1Ow@zed>
Date: Tue, 13 Jan 2026 09:55:10 +0100
From: Jacopo Mondi <jacopo.mondi@...asonboard.com>
To: "jempty.liang" <imntjempty@....com>, 
	Laurent Pinchart <laurent.pinchart@...asonboard.com>, Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: dan.scally@...asonboard.com, jacopo.mondi@...asonboard.com, 
	mchehab@...nel.org, linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: mali-c55: Fix NULL dev stream alert for tpg
 sub-device

Hi Jempty

On Tue, Jan 13, 2026 at 07:57:22AM +0000, jempty.liang wrote:
> Fix "(NULL device *): collect_streams: sub-device 'mali-c55 tpg'
> does not support streams" by setting `sd->dev = mali_c55->dev`
> for isp/resizer/tpg modules.

The missing device name in the error message is just a symptom, I
think this is a geniunely missing part of the subdevice initalization.

I would re-phrase this as

-------------------------------------------------------------------------------
The subdevices registered by the Mali-C55 driver do not have their
'struct device *dev' member initialized. This is visibile when looking
at debug message, as in example:

"(NULL device *): collect_streams: sub-device 'mali-c55 tpg' does not support streams"

Fix this by initializing the *dev field for each subdevice registered
by the Mali-C55 driver.
-------------------------------------------------------------------------------

I wonder if v4l2_device_register_subdev() shouldn't WARN or if return
an error if sd->dev is not initialized. Laurent, Sakari: opinions ?

Thanks
  j

>
> Signed-off-by: jempty.liang <imntjempty@....com>
> ---
>  drivers/media/platform/arm/mali-c55/mali-c55-isp.c     | 1 +
>  drivers/media/platform/arm/mali-c55/mali-c55-resizer.c | 1 +
>  drivers/media/platform/arm/mali-c55/mali-c55-tpg.c     | 1 +
>  3 files changed, 3 insertions(+)
>
> diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-isp.c b/drivers/media/platform/arm/mali-c55/mali-c55-isp.c
> index 497f25fbdd13..ce84aad9f1d5 100644
> --- a/drivers/media/platform/arm/mali-c55/mali-c55-isp.c
> +++ b/drivers/media/platform/arm/mali-c55/mali-c55-isp.c
> @@ -610,6 +610,7 @@ int mali_c55_register_isp(struct mali_c55 *mali_c55)
>  	sd->entity.ops = &mali_c55_isp_media_ops;
>  	sd->entity.function = MEDIA_ENT_F_PROC_VIDEO_ISP;
>  	sd->internal_ops = &mali_c55_isp_internal_ops;
> +	sd->dev = mali_c55->dev;
>  	strscpy(sd->name, MALI_C55_DRIVER_NAME " isp", sizeof(sd->name));
>
>  	isp->pads[MALI_C55_ISP_PAD_SINK_VIDEO].flags = MEDIA_PAD_FL_SINK |
> diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-resizer.c b/drivers/media/platform/arm/mali-c55/mali-c55-resizer.c
> index a8d739af74b6..c4f46651dcee 100644
> --- a/drivers/media/platform/arm/mali-c55/mali-c55-resizer.c
> +++ b/drivers/media/platform/arm/mali-c55/mali-c55-resizer.c
> @@ -1070,6 +1070,7 @@ static int mali_c55_register_resizer(struct mali_c55 *mali_c55,
>  	sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_STREAMS;
>  	sd->entity.function = MEDIA_ENT_F_PROC_VIDEO_SCALER;
>  	sd->internal_ops = &mali_c55_resizer_internal_ops;
> +	sd->dev = mali_c55->dev;
>
>  	rsz->pads[MALI_C55_RSZ_SINK_PAD].flags = MEDIA_PAD_FL_SINK;
>  	rsz->pads[MALI_C55_RSZ_SOURCE_PAD].flags = MEDIA_PAD_FL_SOURCE;
> diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-tpg.c b/drivers/media/platform/arm/mali-c55/mali-c55-tpg.c
> index 1af5d2759a83..894f4cf377af 100644
> --- a/drivers/media/platform/arm/mali-c55/mali-c55-tpg.c
> +++ b/drivers/media/platform/arm/mali-c55/mali-c55-tpg.c
> @@ -370,6 +370,7 @@ int mali_c55_register_tpg(struct mali_c55 *mali_c55)
>  	sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_HAS_EVENTS;
>  	sd->entity.function = MEDIA_ENT_F_CAM_SENSOR;
>  	sd->internal_ops = &mali_c55_tpg_internal_ops;
> +	sd->dev = mali_c55->dev;
>  	strscpy(sd->name, MALI_C55_DRIVER_NAME " tpg", sizeof(sd->name));
>
>  	pad->flags = MEDIA_PAD_FL_SOURCE;
> --
> 2.25.1
>