Re: [PATCH v3 2/8] drm/aspeed: replace struct drm_simple_display_pipe with regular atomic helpers

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] The driver fails to trigger a CRTC modeset when the primary plane's framebuffer pixel format changes, causing the hardware to incorrectly interpret pixels.
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--- Patch [2]: [PATCH v3 2/8] drm/aspeed: replace struct drm_simple_display_pipe with regular atomic helpers ---
Note: The format of this report has been altered to use a free-form summary
due to code recitation restrictions. No inline code quoting is used.

commit 82b41ef8182b1e0fe64dd5371b72b906d9c02892
Author: Ze Huang <ze.huang@oss.qualcomm.com>
Subject: drm/aspeed: replace struct drm_simple_display_pipe with regular atomic helpers

This commit replaces the simple display pipe with explicit plane, CRTC, and
encoder objects. It moves callbacks to plane and CRTC helpers, wires vblank
handling through drm_crtc_funcs, and uses commit-local state for programming.

[Severity: High]
This is a pre-existing issue, but does the driver fail to trigger a CRTC
modeset when the primary plane's framebuffer pixel format changes?

Looking at aspeed_gfx_plane_helper_atomic_check() in 
drivers/gpu/drm/aspeed/aspeed_gfx_crtc.c, there doesn't seem to be a check 
to see if the pixel format has changed between the old and new plane states.

Since the hardware registers for the format (CRT_CTRL1) are only programmed 
during the atomic_enable() path, which requires a full modeset, a format 
change during a simple plane update will only update the DMA address in 
aspeed_gfx_plane_helper_atomic_update(). The format configuration in the 
hardware will remain stale.

Could this lead to corrupted rendering if userspace changes the framebuffer 
format (e.g., from RGB565 to XRGB8888) without changing the display mode? 
Should aspeed_gfx_plane_helper_atomic_check() explicitly set 
crtc_state->mode_changed = true if the new format differs from the old one 
to enforce a full modeset?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260727-drm-simple-kms-removal-v3-0-cd5dc89858c6@oss.qualcomm.com?part=2