Re: [PATCH v5 12/18] phy: rockchip: usbdp: Drop DP HPD handling

[sashiko-bot@kernel.org]

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

Pre-existing issues:
- [High] Lockless access to shared Type-C lane mappings in `rk_udphy_dp_phy_configure` causes data race
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commit 5858d851fd3d6f0beb8a1b3b702ddc25ce1b25b1
Author: Sebastian Reichel <sebastian.reichel@collabora.com>

phy: rockchip: usbdp: Drop DP HPD handling

This commit drops the HPD handling logic from the USBDP PHY. The registers
involved require the display controller power domain being enabled, so the HPD
signal should be handled by the displayport controller itself.

> diff --git a/drivers/phy/rockchip/phy-rockchip-usbdp.c b/drivers/phy/rockchip/phy-rockchip-usbdp.c
> --- a/drivers/phy/rockchip/phy-rockchip-usbdp.c
> +++ b/drivers/phy/rockchip/phy-rockchip-usbdp.c

[ ... ]

> static int rk_udphy_dp_phy_configure(struct phy *phy,
> 				     union phy_configure_opts *opts)
> {

[ ... ]

> 	if (dp->set_voltages) {
> 		for (i = 0; i < udphy->lanes; i++) {
> 			lane = udphy->dp_lane_sel[i];
> 			switch (udphy->link_rate) {
> 			case 1620:
> 			case 2700:

[Severity: High]
This isn't a bug introduced by this patch, but I noticed a potential data
race here. Does this loop access udphy->dp_lane_sel and
udphy->lane_mux_sel safely?

These arrays define the active Type-C DP lane mapping and are updated by
asynchronous Type-C subsystem events in rk_udphy_orien_sw_set() and
rk_udphy_typec_mux_set() under the protection of udphy->mutex.

Since rk_udphy_dp_phy_configure() does not hold udphy->mutex (only the
framework-level phy->mutex), could a concurrent Type-C cable orientation
or mode switch cause this code to read a partially updated lane mapping?

This might lead to incorrect DP PHY register programming, configuring the
wrong hardware lanes and causing link training or display failures.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260612-rockchip-usbdp-cleanup-v5-0-efc83069869f@collabora.com?part=12

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