From mboxrd@z Thu Jan  1 00:00:00 1970
From: Claude Code Review Bot <claude-review@example.com>
To: dri-devel-reviews@example.com
Subject: Claude review: drm/rockchip: cdn-dp: Support handle lane info without extcon
Date: Mon, 25 May 2026 21:00:52 +1000
Message-ID: <review-patch4-20260521032854.103-5-kernel@airkyi.com>
In-Reply-To: <20260521032854.103-5-kernel@airkyi.com>
References: <20260521032854.103-1-kernel@airkyi.com> <20260521032854.103-5-kernel@airkyi.com>
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Patch Review

Makes the extcon device optional in CDN-DP, falling back to `phy_get_bus_wi=
dth()` for lane count.

**Issue: Potentially incorrect filter condition in probe**
```c
-       if (IS_ERR(extcon) || IS_ERR(phy))
+       if (IS_ERR(phy) || PTR_ERR(extcon) !=3D -ENODEV)
            continue;
```
The original skips the port if either extcon OR phy is an error. The new co=
de skips if phy is an error OR if `PTR_ERR(extcon) !=3D -ENODEV`. But if `e=
xtcon` is **valid** (not an error), then `PTR_ERR(extcon)` is undefined beh=
avior =E2=80=94 it would cast a valid pointer to a long and compare it agai=
nst `-ENODEV`. This condition should be:
```c
if (IS_ERR(phy) || (IS_ERR(extcon) && PTR_ERR(extcon) !=3D -ENODEV))
    continue;
```
The intent is: skip if phy fails, or if extcon failed with something other =
than `-ENODEV` (meaning extcon is genuinely absent vs. a real error like `-=
EPROBE_DEFER`). The current code is **buggy for the case where extcon is va=
lid**.

Wait =E2=80=94 re-reading: extcon is fetched above with `extcon_find_edev_b=
y_node`. If it returns a valid pointer, `PTR_ERR()` of a valid pointer is n=
ot `-ENODEV`, so the `continue` would fire, skipping valid ports. This is a=
 real bug.

**Issue: `property.intval =3D 0` default for polarity**
```c
property.intval =3D 0;
if (port->extcon) {
    ret =3D extcon_get_property(port->extcon, EXTCON_DISP_DP,
                  EXTCON_PROP_USB_TYPEC_POLARITY, &property);
```
When extcon is absent, polarity defaults to 0, which assumes normal polarit=
y. This seems reasonable but should be documented or verified against the h=
ardware behavior when the Type-C controller is managing polarity via the PH=
Y directly.

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