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/connector: hdmi: Add support for 'link bpc' property
Date: Tue, 31 Mar 2026 17:31:19 +1000
Message-ID: <review-patch2-20260330-link-bpc-v6-2-ff124af93e48@collabora.com>
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References: <20260330-link-bpc-v6-0-ff124af93e48@collabora.com> <20260330-link-bpc-v6-2-ff124af93e48@collabora.com>
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Patch Review

**Issue 1 (bug): `link_bpc` only set when output_bpc changes, not on initia=
l modeset**

```c
if (old_conn_state->hdmi.broadcast_rgb !=3D new_conn_state->hdmi.broadcast_=
rgb ||
    old_conn_state->hdmi.output_bpc !=3D new_conn_state->hdmi.output_bpc ||
    old_conn_state->hdmi.output_format !=3D new_conn_state->hdmi.output_for=
mat) {
        struct drm_crtc *crtc =3D new_conn_state->crtc;
        struct drm_crtc_state *crtc_state;

        new_conn_state->link_bpc =3D new_conn_state->hdmi.output_bpc;
```

The `link_bpc` assignment is **inside** the `if` block that only triggers w=
hen broadcast_rgb, output_bpc, or output_format have changed from the old s=
tate. On the **first** modeset (or any modeset where these values happen to=
 be the same as previous), `link_bpc` will remain at its default of 0 (zero=
-initialized connector state), which is below the range minimum of 8.

The `commit_tail` code will then see `old_conn_state->link_bpc (0) !=3D new=
_conn_state->link_bpc (0)` =E2=80=94 actually they'd be equal so it wouldn'=
t fire, but the property would remain stale at its initial `max_bpc` value =
rather than reflecting the actual output_bpc.

The assignment should be moved **outside** the if block, to unconditionally=
 set `link_bpc` to `hdmi.output_bpc`:

```c
new_conn_state->link_bpc =3D new_conn_state->hdmi.output_bpc;

if (old_conn_state->hdmi.broadcast_rgb !=3D new_conn_state->hdmi.broadcast_=
rgb ||
    ...
```

This was actually what the cover letter's diff stat area suggests (the `+` =
line before the `crtc_state` block), but in the actual diff the assignment =
ended up inside the conditional. Looking at the diff more carefully, the `+=
` lines show it placed right after the opening brace of the if block. This =
is a real bug =E2=80=94 on initial enable the link_bpc won't be set to the =
actual value.

**Patch 2 otherwise looks correct:** The `drmm_connector_hdmi_init` integra=
tion properly attaches the property after `max_bpc` is set up, and the erro=
r return is properly wired.

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