Re: [PATCH 1/3] arm64: dts: qcom: msm8916: Disable disconnected DSI

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [High] arm64: dts: qcom: msm8916: broken display and probe crash on
  apq8016 boards
--

commit 84868fbeac14d1ada5236c28cee63ebec6ea8fbd
Author: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>

arm64: dts: qcom: msm8916: Disable disconnected DSI

This commit disables mdss_dsi0 and mdss_dsi0_phy by default in msm8916.dtsi
and enables them in four Samsung board DTS files that define a DSI panel.

> diff --git a/arch/arm64/boot/dts/qcom/msm8916.dtsi b/arch/arm64/boot/dts/qcom/msm8916.dtsi
> index e39743e220438..7d351cd15f901 100644
> --- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
> @@ -1634,6 +1634,8 @@ mdss_dsi0: dsi@1a98000 {
>  				#address-cells = <1>;
>  				#size-cells = <0>;
>  
> +				status = "disabled";
> +
>  				ports {
>  					#address-cells = <1>;
>  					#size-cells = <0>;
> @@ -1668,6 +1670,8 @@ mdss_dsi0_phy: phy@1a98300 {
>  				clocks = <&gcc GCC_MDSS_AHB_CLK>,
>  					 <&xo_board>;
>  				clock-names = "iface", "ref";
> +
> +				status = "disabled";
>  			};
>  		};

[Severity: High]
Does disabling mdss_dsi0 and mdss_dsi0_phy here break display and audio on
apq8016-sbc.dts and apq8016-schneider-hmibsc.dts, and cause a NULL pointer
dereference during boot on apq8016-schneider-hmibsc.dts?

Both APQ8016 boards enable &mdss and connect &mdss_dsi0_out to an I2C
ADV7533 DSI-to-HDMI bridge (remote-endpoint = <&adv7533_in>) instead of a
child panel node, without setting status = "okay" on &mdss_dsi0 or
&mdss_dsi0_phy.  With mdss_dsi0 disabled, adv7533_parse_dt() fails with
-ENODEV because of_graph_get_remote_node() sees an unavailable remote parent,
which also prevents the &sound card referencing &adv_bridge from probing.

In addition, on apq8016-schneider-hmibsc.dts where &mdss is enabled and &gpu
remains disabled, add_mdp_components() skips the disabled mdss_dsi0 node and
leaves match as NULL.  mdp5_dev_probe() -> msm_drv_probe() then passes
match = NULL to component_master_add_with_match(), which dereferences
match->num.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261110-display-msm-of-graph-v1-0-0f3106f817b4@oss.qualcomm.com?part=1