[PATCH] drm/msm: enable separate_gpu_kms by default

[PATCH] drm/msm: enable separate_gpu_kms by default

[Mahadevan P]

On targets with multiple display subsystems, such as SA8775P, the GPU
binds to the first display subsystem that probes. This implicit binding
prevents subsequent display subsystems from probing successfully,
breaking multi-display support.

Enable separate_gpu_kms by default to decouple GPU and display subsystem
probing. This allows each display subsystem to initialize independently,
ensuring that all display subsystems are probed.

Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
---
Depends on:
	https://lore.kernel.org/lkml/20260124-adreno-module-table-v1-1-9c2dbb2638b4@oss.qualcomm.com/
	https://lore.kernel.org/all/20260217071420.2240380-1-mkuntuma@qti.qualcomm.com/
---
 drivers/gpu/drm/msm/msm_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index ed2a61c66ac9..65119fb3dfa2 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -54,7 +54,7 @@ static bool modeset = true;
 MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
 module_param(modeset, bool, 0600);
 
-static bool separate_gpu_kms;
+static bool separate_gpu_kms = true;
 MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");
 module_param(separate_gpu_kms, bool, 0400);
 

---
base-commit: 50f68cc7be0a2cbf54d8f6aaf17df32fb01acc3f
change-id: 20260219-seperate_gpu_kms-97870cb36aaf

Best regards,
-- 
Mahadevan P <mahadevan.p@oss.qualcomm.com>

Claude review: drm/msm: enable separate_gpu_kms by default

[Claude Code Review Bot]

Overall Series Review

Subject: drm/msm: enable separate_gpu_kms by default
Author: Mahadevan P <mahadevan.p@oss.qualcomm.com>
Patches: 1
Reviewed: 2026-02-23T05:46:34.073865

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This is a single-patch series that changes the default value of the `separate_gpu_kms` module parameter in the MSM DRM driver from `false` to `true`. The effect is to decouple GPU and display subsystem probing by default, so each display subsystem initializes independently rather than the GPU binding to the first display subsystem that probes. The commit message explains the motivation: on multi-display targets like SA8775P, the old default prevents subsequent display subsystems from probing.

The change itself is trivially correct -- it flips a boolean default. However, the `MODULE_PARM_DESC` string becomes inaccurate after this change, and there is a pre-existing naming mismatch between the description and the parameter that this patch should address while it is changing the default.

The patch also declares dependencies on two other patch series. Whether this default change is safe without those dependencies being merged first is an important consideration that isn't addressed in the commit message.

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Generated by Claude Code Patch Reviewer

Claude review: drm/msm: enable separate_gpu_kms by default

[Claude Code Review Bot]

Patch Review

> -static bool separate_gpu_kms;
> +static bool separate_gpu_kms = true;
>  MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");

The `MODULE_PARM_DESC` text says "0=single DRM device for both GPU and display (default)" but after this patch the default is now 1 (separate). The description should be updated to reflect the new default, something like "1=two DRM devices (default)" and removing "(default)" from the 0 option.

Additionally, there is a pre-existing naming mismatch: `MODULE_PARM_DESC` refers to `separate_gpu_drm` while `module_param` uses `separate_gpu_kms`. This means the description visible via `modinfo` is associated with a parameter name (`separate_gpu_drm`) that doesn't actually exist as a parameter. Since this patch is already touching this line, it would be a good opportunity to fix the `MODULE_PARM_DESC` name to match `separate_gpu_kms`.

The commit message mentions this is needed for SA8775P targets with multiple display subsystems, but doesn't discuss potential regressions on existing single-display targets. Changing a default like this affects all MSM platforms. Is there any risk of userspace breakage on platforms that currently expect a single DRM device? If userspace (e.g., display managers, compositors) on existing deployed systems is configured to find the GPU via the combined DRM device node, changing the default could break those setups. Some discussion of backwards compatibility or testing coverage in the commit message would be helpful.

The patch declares dependencies on two other series. Does this patch function correctly without those dependencies, or would applying it standalone cause probe failures? The commit message should clarify this.

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Generated by Claude Code Patch Reviewer