Re: [PATCH 07/12] drm/panic: Retry in dispatch function if panic output fails

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Removing the internal fallback from `draw_panic_screen_qr_code` breaks the `drm_panic` KUnit tests.
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--- Patch [7]: [PATCH 07/12] drm/panic: Retry in dispatch function if panic output fails ---
commit 23392eb57457ad383d9c4741f6fc2f3c107aabb3
Author: Thomas Zimmermann <[email protected]>

drm/panic: Retry in dispatch function if panic output fails

On failed output of QR codes and kmsg buffers, fall back to a user
message. QR-code output already did this internally, but now formally
support it in drm_panic_dispatch(). Streamlines the existing logic.

> --- a/drivers/gpu/drm/drm_panic.c
> +++ b/drivers/gpu/drm/drm_panic.c
[ ... ]
> @@ -816,15 +816,6 @@ static int _draw_panic_screen_qr_code(struct drm_scanout_buffer *sb,
>  	drm_panic_blit(sb, &r_qr, qr_image, qr_pitch, scale, fg_color);
>  	return 0;
>  }
> -
> -static int draw_panic_screen_qr_code(struct drm_scanout_buffer *sb,
> -				     u32 fg_color, u32 bg_color,
> -				     unsigned int qr_version)
> -{
> -	if (_draw_panic_screen_qr_code(sb, fg_color, bg_color, qr_version))
> -		draw_panic_screen_user(sb, fg_color, bg_color);
> -	return 0;
> -}

[Severity: Medium]
Does removing this fallback cause the drm_panic KUnit tests to fail?

Looking at the test suite in drivers/gpu/drm/tests/drm_panic_test.c, it
calls this function directly without going through the new dispatch logic:

static int draw_panic_screen_qr_code_default(struct drm_scanout_buffer *sb)
{
	return draw_panic_screen_qr_code(sb, 0x00ffffff, 0x00000000, 40);
}

When tested with a small resolution like 300x200, the scale evaluates to 0
and returns -ENOSPC. Previously, this wrapper caught the error, fell back
to draw_panic_screen_user, and safely returned 0, satisfying the KUnit
check.

Since the fallback was moved to draw_panic_dispatch and the test calls
the lower-level function directly, will this now propagate the -ENOSPC
error and spuriously fail the test?

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=7