From mboxrd@z Thu Jan  1 00:00:00 1970
From: Claude Code Review Bot <claude-review@example.com>
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Subject: Claude review: drm/msm/hdmi: Fix wrong CTRL1 register used in writing info frames
Date: Thu, 12 Mar 2026 06:46:34 +1000
Message-ID: <review-patch1-20260311191620.245394-2-krzysztof.kozlowski@oss.qualcomm.com>
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Patch Review

**Bug analysis:** The original code (from commit `384d2b03d0a1`) converted unconditional register writes to read-modify-write sequences but read from `REG_HDMI_INFOFRAME_CTRL1` while applying masks for `HDMI_INFOFRAME_CTRL0` fields and writing to `REG_HDMI_INFOFRAME_CTRL0`. This means the CTRL0 register was being corrupted with bits from CTRL1, and any existing CTRL0 bits that should have been preserved were lost.

**Fix correctness:** The fix changes both occurrences to read from `REG_HDMI_INFOFRAME_CTRL0`, making the read-modify-write consistent:

```c
val = hdmi_read(hdmi, REG_HDMI_INFOFRAME_CTRL0);  // was CTRL1
val |= HDMI_INFOFRAME_CTRL0_AVI_SEND |
       HDMI_INFOFRAME_CTRL0_AVI_CONT;
hdmi_write(hdmi, REG_HDMI_INFOFRAME_CTRL0, val);
```

and similarly for the audio infoframe path:

```c
val = hdmi_read(hdmi, REG_HDMI_INFOFRAME_CTRL0);  // was CTRL1
val |= HDMI_INFOFRAME_CTRL0_AUDIO_INFO_SEND |
       HDMI_INFOFRAME_CTRL0_AUDIO_INFO_CONT |
       HDMI_INFOFRAME_CTRL0_AUDIO_INFO_SOURCE |
       HDMI_INFOFRAME_CTRL0_AUDIO_INFO_UPDATE;
hdmi_write(hdmi, REG_HDMI_INFOFRAME_CTRL0, val);
```

Looking at the post-patch source (lines 156-164), the pattern is now consistent with the immediately following block that correctly does read-modify-write on CTRL1 for CTRL1-specific fields (`HDMI_INFOFRAME_CTRL1_AVI_INFO_LINE`).

**Minor observation:** The `|=` operation (rather than clearing bits first with a mask) means these "send/cont" bits are only ever set, never cleared through this path. This is fine since the `clear_avi_infoframe` / `clear_audio_infoframe` functions are called at the start of each write function to handle the clearing.

**Tags:** Fixes tag, Cc: stable, and Signed-off-by are all present and appropriate.

**No issues found.** 

Reviewed-by recommendation: This patch is correct and ready to merge.

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