Re: [PATCH v5 2/2] drm/panel: Add Ilitek ILI9488 controller driver

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Missing NULL pointer check for the return value of device_get_match_data() leads to a kernel panic.
- [Low] The driver calls devm_drm_panel_add(), which is a non-existent function in the DRM subsystem, causing a compilation failure.
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commit 279cca9ce157e0fd7f3b036067b2491d2e280fa4
Author: Igor Reznichenko <igor@reznichenko.net>

drm/panel: Add Ilitek ILI9488 controller driver

This commit adds support for the Ilitek ILI9488 DSI controller used in the
FocusLCDs E35GH-I-MW800-CB 320x480 MIPI DSI panel.

> diff --git a/drivers/gpu/drm/panel/panel-ilitek-ili9488.c b/drivers/gpu/drm/panel/panel-ilitek-ili9488.c
> new file mode 100644
> index 0000000000000..7302766034fc9
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-ilitek-ili9488.c

[ ... ]

> +static int ili9488_dsi_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct ili9488 *ili;
> +	int i, ret;
> +
> +	ili = devm_drm_panel_alloc(dev, struct ili9488, panel, &ili9488_funcs,
> +				   DRM_MODE_CONNECTOR_DSI);
> +	if (IS_ERR(ili))
> +		return PTR_ERR(ili);
> +
> +	ili->desc = device_get_match_data(dev);
> +	ili->dsi = dsi;
> +
> +	dsi->mode_flags = ili->desc->mode_flags;

[Severity: High]
Is it possible for device_get_match_data() to return NULL here?

If the device is instantiated without matching device tree data (for example,
via a manual sysfs driver bind to a DSI device created without an OF node),
device_get_match_data() will return NULL because the driver lacks an id_table
and only provides an of_match_table. 

Dereferencing ili->desc immediately after might lead to a NULL pointer 
dereference in these cases.

[ ... ]

> +	ret = drm_panel_of_backlight(&ili->panel);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to get backlight\n");
> +
> +	ili->panel.prepare_prev_first = true;
> +
> +	ret = devm_drm_panel_add(dev, &ili->panel);

[Severity: Low]
Does devm_drm_panel_add() exist in the DRM subsystem?

Looking at the DRM panel API, while there is devm_drm_panel_alloc() and
drm_panel_add(), there does not appear to be a devm-managed version of
drm_panel_add(). Will this cause a build failure when compiling the driver?

> +	if (ret)
> +		return ret;
> +
> +	ret = devm_mipi_dsi_attach(dev, dsi);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "failed to attach to DSI host\n");
> +
> +	return 0;
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260529062836.203990-1-igor@reznichenko.net?part=2