[PATCH] drm/bridge: synopsys: dw-dp: fix bool function returning negative error code

[PATCH] drm/bridge: synopsys: dw-dp: fix bool function returning negative error code

[Bob ynn]

From: yanlonglong <yanlonglong@kylinos.cn>

The function dw_dp_video_need_vsc_sdp() is declared to return bool, but
it returns -EINVAL when dw_dp_get_bridge_state() fails. Since -EINVAL is
a non-zero value (-22), it is implicitly converted to true, which is the
opposite of the intended behavior

Fixes: 86eecc3a9c2e("drm/bridge: synopsys: Add DW DPTX Controller support library")
Signed-off-by: yanlonglong <yanlonglong@kylinos.cn>
---
 drivers/gpu/drm/bridge/synopsys/dw-dp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index 21541be094c4..7b99d91b3456 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -1143,7 +1143,7 @@ static bool dw_dp_video_need_vsc_sdp(struct dw_dp *dp)
 
 	state = dw_dp_get_bridge_state(dp);
 	if (!state)
-		return -EINVAL;
+		return false;
 
 	if (!link->vsc_sdp_supported)
 		return false;
-- 
2.43.0

Claude review: drm/bridge: synopsys: dw-dp: fix bool function returning negative error code

[Claude Code Review Bot]

Overall Series Review

Subject: drm/bridge: synopsys: dw-dp: fix bool function returning negative error code
Author: Bob ynn <yanlonglong@kylinos.cn>
Patches: 1
Reviewed: 2026-05-16T10:13:40.480504

---

This is a single-patch fix for a real bug: the bool-returning function `dw_dp_video_need_vsc_sdp()` was returning `-EINVAL` (a non-zero integer) on error, which gets implicitly converted to `true`. This would incorrectly cause the VSC SDP flag (`DP_MSA_MISC_COLOR_VSC_SDP`) to be set in the MSA when `dw_dp_get_bridge_state()` fails, which is the opposite of safe/correct behavior. Returning `false` on failure is the right conservative choice — if we can't determine the bridge state, we shouldn't claim a VSC SDP is needed.

The fix is correct, minimal, and appropriate. **Recommend: Accept.**

---
Generated by Claude Code Patch Reviewer

Claude review: drm/bridge: synopsys: dw-dp: fix bool function returning negative error code

[Claude Code Review Bot]

Patch Review

**Analysis:** The function `dw_dp_video_need_vsc_sdp()` at line 1139 returns `bool`. Before the patch, the error path at line 1145 was:

```c
if (!state)
    return -EINVAL;
```

Since `-EINVAL` is `-22`, and C implicitly converts any non-zero integer to `true` for a `bool` return, this error path was silently returning `true` — indicating a VSC SDP *is* needed, when the function actually couldn't determine the answer. The sole caller at line 1163:

```c
if (dw_dp_video_need_vsc_sdp(dp))
    misc |= DP_MSA_MISC_COLOR_VSC_SDP;
```

would incorrectly set the VSC SDP color bit in the MSA miscellaneous field on failure.

**The fix** — changing to `return false` — is correct. Returning `false` on failure is the safe default: it avoids setting the VSC SDP flag when state is unavailable, which matches the behavior of the other early-return (`!link->vsc_sdp_supported`) in the same function.

**Minor nits on the commit message:**
- The Fixes tag formatting has a minor style issue: there should be a space before the parenthesis: `Fixes: 86eecc3a9c2e ("drm/bridge:...")` (kernel convention uses `("...)`  not `("...)`). This is cosmetic but maintainers sometimes ask for it to be fixed.
- The commit message body is missing a period at the end of the sentence ("the opposite of the intended behavior" → "the opposite of the intended behavior.").

**Verdict:** The code change itself is correct and complete. No functional concerns.

---
Generated by Claude Code Patch Reviewer

[PATCH] drm/bridge: synopsys: dw-dp: fix bool function returning negative error code

[Bob ynn]

From: yanlonglong <yanlonglong@kylinos.cn>

The function dw_dp_video_need_vsc_sdp() is declared to return bool, but
it returns -EINVAL when dw_dp_get_bridge_state() fails. Since -EINVAL is
a non-zero value (-22), it is implicitly converted to true, which is the
opposite of the intended behavior

Fixes: 86eecc3a9c2e("drm/bridge: synopsys: Add DW DPTX Controller support library")
Signed-off-by: yanlonglong <yanlonglong@kylinos.cn>
---
 drivers/gpu/drm/bridge/synopsys/dw-dp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index 21541be094c4..7b99d91b3456 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -1143,7 +1143,7 @@ static bool dw_dp_video_need_vsc_sdp(struct dw_dp *dp)
 
 	state = dw_dp_get_bridge_state(dp);
 	if (!state)
-		return -EINVAL;
+		return false;
 
 	if (!link->vsc_sdp_supported)
 		return false;
-- 
2.43.0