Re: [PATCH] drm/sun4i: Remove dependency on DRM simple helpers

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] This problem wasn't introduced by this patch, but the return value of `drm_encoder_init()` is ignored in `sun8i_dw_hdmi_bind()`, which leads to a potential kernel panic on the error path.
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commit 2d6b8f73fd3be1e78f02ca32197b62b5da0fb174
Author: Diogo Silva <diogompaissilva@gmail.com>

drm/sun4i: Remove dependency on DRM simple helpers

Simple KMS helper are deprecated since they only add an intermediate layer
between drivers and the atomic modesetting. This patch removes the dependency
on drm simple helpers from sun4i DRM drivers.

> diff --git a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
> index 96532709c2a7e..9694ad142a7de 100644
> --- a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
> +++ b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
[ ... ]
> @@ -180,7 +183,8 @@ static int sun8i_dw_hdmi_bind(struct device *dev, struct device *master,
>  		goto err_disable_clk_tmds;
>  
>  	drm_encoder_helper_add(encoder, &sun8i_dw_hdmi_encoder_helper_funcs);
> -	drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_TMDS);
> +	drm_encoder_init(drm, encoder, &sun8i_dw_hdmi_encoder_funcs,
> +			 DRM_MODE_ENCODER_TMDS, NULL);

[Severity: High]
This isn't a bug introduced by this patch, but the return value of
drm_encoder_init() is ignored here in sun8i_dw_hdmi_bind().

If drm_encoder_init() fails, the encoder remains uninitialized. If a
subsequent initialization step like dw_hdmi_bind() then fails, the
execution jumps to the cleanup_encoder error path:

    cleanup_encoder:
            drm_encoder_cleanup(encoder);

Could calling drm_encoder_cleanup() on an uninitialized encoder cause a
kernel panic due to dereferencing NULL pointers (such as encoder->dev or a
zero-initialized list_head)? Should the return code of drm_encoder_init()
be checked and handled here?

>  
>  	plat_data->mode_valid = hdmi->quirks->mode_valid;
>  	plat_data->use_drm_infoframe = hdmi->quirks->use_drm_infoframe;

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Sashiko AI review · https://sashiko.dev/#/patchset/20260623-sun4i_simple-v1-1-fa6696df1fad@gmail.com?part=1