Re: [PATCH v5 15/21] drm: bridge: dw_hdmi: Add common suspend helper

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] NULL pointer dereference in dw_hdmi_rockchip_suspend if system suspends before component bind.
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commit abc5ed0537352dd111abc436d5fc9ba8787addd8
Author: Jonas Karlman <jonas@kwiboo.se>

drm: bridge: dw_hdmi: Add common suspend helper

This commit adds a dw_hdmi_suspend() helper as the suspend-side counterpart
to dw_hdmi_resume() and calls it from the i.MX8MP, Amlogic and Rockchip
platform PM suspend callbacks. This routes suspend handling through common
dw-hdmi code.

> diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
> index 0dc1eb5d2ae39..9677424075eba 100644
> --- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
> +++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
> @@ -651,6 +651,15 @@ static void dw_hdmi_rockchip_remove(struct platform_device *pdev)
>  	component_del(&pdev->dev, &dw_hdmi_rockchip_ops);
>  }
>  
> +static int __maybe_unused dw_hdmi_rockchip_suspend(struct device *dev)
> +{
> +	struct rockchip_hdmi *hdmi = dev_get_drvdata(dev);
> +
> +	dw_hdmi_suspend(hdmi->hdmi);

Could hdmi be NULL here if the system suspends before the component is bound?

In dw_hdmi-rockchip.c, the probe function calls component_add(), so the
platform device is registered before the driver's private data is allocated
and set via platform_set_drvdata() during the bind callback.

If a system suspend occurs after probe but before bind (e.g., if the DRM
master is deferred waiting on other components), dev_get_drvdata(dev) will
return NULL. Accessing hdmi->hdmi would then cause a NULL pointer
dereference.

Although the pre-existing dw_hdmi_rockchip_resume() function suffers from the
same missing check, this patch introduces the issue into the newly added
suspend path.

Should an explicit check for !hdmi be added here, similar to how it is
handled in meson_dw_hdmi_pm_suspend()?

> +
> +	return 0;
> +}
> +
>  static int __maybe_unused dw_hdmi_rockchip_resume(struct device *dev)
>  {

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Sashiko AI review · https://sashiko.dev/#/patchset/20260510124111.1226584-1-jonas@kwiboo.se?part=15