Re: [PATCH v10 20/36] phy: rockchip: usbdp: Factor out lane_mux_sel setup

[sashiko-bot@kernel.org]

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

Pre-existing issues:
- [High] Overwriting udphy->dp_lanes in rk_udphy_set_typec_state destroys the hardware lane limit, leading to uninitialized array access.
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commit b5a0ae84556b392b692f17a4e792243cb346f579
Author: Sebastian Reichel <sebastian.reichel@collabora.com>

phy: rockchip: usbdp: Factor out lane_mux_sel setup

This commit factors out the Type-C state logic into a new helper function
rk_udphy_set_typec_state() to reduce code duplication when configuring the
USB+DP lane_mux_sel.

> diff --git a/drivers/phy/rockchip/phy-rockchip-usbdp.c b/drivers/phy/rockchip/phy-rockchip-usbdp.c
> index 4b454798c4ed4..4e54020d17551 100644
> --- a/drivers/phy/rockchip/phy-rockchip-usbdp.c
> +++ b/drivers/phy/rockchip/phy-rockchip-usbdp.c
> @@ -582,6 +582,42 @@ static void rk_udphy_mode_set(struct rk_udphy *udphy, u8 mode)
>  	udphy->mode = mode;
>  }
>  
> +static void rk_udphy_set_typec_state(struct rk_udphy *udphy, unsigned long state)
> +{
> +	u8 mode;
> +
> +	switch (state) {
> +	case TYPEC_DP_STATE_C:
> +	case TYPEC_DP_STATE_E:
> +		udphy->lane_mux_sel[0] = PHY_LANE_MUX_DP;
> +		udphy->lane_mux_sel[1] = PHY_LANE_MUX_DP;
> +		udphy->lane_mux_sel[2] = PHY_LANE_MUX_DP;
> +		udphy->lane_mux_sel[3] = PHY_LANE_MUX_DP;
> +		mode = UDPHY_MODE_DP;
> +		udphy->dp_lanes = 4;
                ^^^^^^^^^^^^^^^^^^^
[Severity: High]
This is a pre-existing issue, but does overwriting udphy->dp_lanes here
destroy the hardware lane limit?

The variable udphy->dp_lanes seems to be overloaded. It is initially
populated from the device tree to represent the physical hardware lane
limit (e.g., 2 lanes). However, it is unconditionally overwritten here
to represent the requested Type-C state.

If a 2-lane PHY receives a 4-lane Type-C request, udphy->dp_lanes becomes 4.
Does this defeat the hardware limit check if (dp->lanes > udphy->dp_lanes)
in rk_udphy_dp_phy_verify_lanes() (added in a subsequent patch in this
series)?

If the hardware limit check is defeated, the DP controller might configure
4 lanes, causing rk_udphy_dp_phy_configure() to iterate 4 times and access
uninitialized elements in the dp_lane_sel array:

drivers/phy/rockchip/phy-rockchip-usbdp.c:rk_udphy_dp_phy_configure()
        ...
	if (dp->set_voltages) {
		for (i = 0; i < udphy->lanes; i++) {
			lane = udphy->dp_lane_sel[i];
        ...

Since dp_lane_sel[2] and dp_lane_sel[3] would be 0 (due to devm_kzalloc),
could this result in lane 0 being misconfigured multiple times, overriding
its intended settings and corrupting the USB3 state?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260703-rockchip-usbdp-cleanup-v10-0-a392711ca8a9@collabora.com?part=20