Re: [PATCH v3 7/9] drm/panel: novatek-nt36672a: Add Tianma panel for Xiaomi Mi A2

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] drm/panel: nt36672a: regulator leak in nt36672a_panel_prepare() error path
--

commit 55c52ad322748f420246cd3fb678326e61c47140
Author: Alexey Minnekhanov <alexeymin@minlexx.ru>

    drm/panel: novatek-nt36672a: Add Tianma panel for Xiaomi Mi A2
    
    Add support for Tianma TL060FVXS16-00 video mode panel based on
    Novatek NT36672A, used in Xiaomi Mi A2 smartphone (xiaomi-jasmine).
    It shares some code with already supported panel in this driver
    for xiaomi-lavender, so we can reuse the same panel deinit function.

> diff --git a/drivers/gpu/drm/panel/panel-novatek-nt36672a.c b/drivers/gpu/drm/panel/panel-novatek-nt36672a.c
> index d356348d39608..48dff2279b0e9 100644
> --- a/drivers/gpu/drm/panel/panel-novatek-nt36672a.c
> +++ b/drivers/gpu/drm/panel/panel-novatek-nt36672a.c
[ ... ]
> @@ -552,6 +575,39 @@ static const struct nt36672a_panel_desc tianmaplus_e7t_tulip_panel_desc = {
>  	.send_deinit_cmds = lavender_tulip_deinit_cmds,
>  };
>  
> +static const struct drm_display_mode tianma_jasmine_panel_default_mode = {
[ ... ]
> +static const struct nt36672a_panel_desc tianma_jasmine_panel_desc = {
> +	.display_mode = &tianma_jasmine_panel_default_mode,
> +
> +	.width_mm = 68,
> +	.height_mm = 136,
> +
> +	.mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
> +			MIPI_DSI_CLOCK_NON_CONTINUOUS,
> +	.format = MIPI_DSI_FMT_RGB888,
> +	.lanes = 4,
> +	.send_init_cmds = tianma_jasmine_init_cmds,

[Severity: Medium]
If sending the initialization commands fails in nt36672a_panel_prepare(), does
this code leak the regulator resources?

Looking at nt36672a_panel_prepare(), it calls nt36672a_panel_power_on() which
enables the regulators, and then calls send_init_cmds():

drivers/gpu/drm/panel/panel-novatek-nt36672a.c:nt36672a_panel_prepare() {
	...
	dsi_ctx.accum_err = nt36672a_panel_power_on(pinfo);

	/* send init cmds */
	if (pinfo->desc->send_init_cmds)
		pinfo->desc->send_init_cmds(&dsi_ctx);

	if (dsi_ctx.accum_err < 0)
		gpiod_set_value(pinfo->reset_gpio, 0);

	return dsi_ctx.accum_err;
}

If send_init_cmds() fails, the error path returns early without calling
nt36672a_panel_power_off() or regulator_bulk_disable().

Furthermore, because drm_panel_prepare() sees a failure, it does not set
panel->prepared = true. Consequently, any future call to drm_panel_unprepare()
will return early and skip calling the panel's .unprepare function, leaving
the regulators (vddio, vddpos, vddneg) permanently enabled.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261011-nt36672a-panels-v3-0-9ea238627f8a@minlexx.ru?part=7