[PATCH v7 08/27] phy: rockchip: usbdp: Limit DP lane count to muxed lanes

[Sebastian Reichel]

In theory the DP controller could request 4 lanes when the PHY is
restricted to 2 lanes as the other half is used by USB3.

With the current user (DW-DP) this cannot happen, but as the check is
cheap and users might change in the future protect things accordingly.
Not doing so would corrupt USB3 usage by the following code configuring
the voltages.

Fixes: 2f70bbddeb45 ("phy: rockchip: add usbdp combo phy driver")
Reported-by: Sashiko <sashiko-bot at kernel.org>
Closes: https://lore.kernel.org/linux-phy/20260612165546.98E1F1F000E9@smtp.kernel.org/
Signed-off-by: Sebastian Reichel <sebastian.reichel at collabora.com>
---
 drivers/phy/rockchip/phy-rockchip-usbdp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/phy/rockchip/phy-rockchip-usbdp.c b/drivers/phy/rockchip/phy-rockchip-usbdp.c
index 121dd78d8c16..2324f9050f63 100644
--- a/drivers/phy/rockchip/phy-rockchip-usbdp.c
+++ b/drivers/phy/rockchip/phy-rockchip-usbdp.c
@@ -1132,6 +1132,9 @@ static int rk_udphy_dp_phy_verify_link_rate(struct rk_udphy *udphy,
 static int rk_udphy_dp_phy_verify_lanes(struct rk_udphy *udphy,
 					struct phy_configure_opts_dp *dp)
 {
+	if (dp->lanes > udphy->dp_lanes)
+		return -EINVAL;
+
 	switch (dp->lanes) {
 	case 1:
 	case 2:

-- 
2.53.0