[PATCH AUTOSEL 6.17] drm/amd/pm: refine amdgpu pm sysfs node error code

[Sasha Levin <sashal@kernel.org>]

From: Yang Wang <kevinyang.wang@amd.com>

[ Upstream commit cf32515a70618c0fb2319bd4a855f4d9447940a8 ]

v1:
Returns different error codes based on the scenario to help the user app understand
the AMDGPU device status when an exception occurs.

v2:
change -NODEV to -EBUSY.

Signed-off-by: Yang Wang <kevinyang.wang@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

YES

- What changed
  - The function `amdgpu_pm_dev_state_check()` now returns `-EBUSY`
    instead of `-EPERM` when the device is in GPU reset or system
    suspend:
    - `drivers/gpu/drm/amd/pm/amdgpu_pm.c:112`: `if
      (amdgpu_in_reset(adev)) return -EBUSY;` (was `-EPERM`)
    - `drivers/gpu/drm/amd/pm/amdgpu_pm.c:115`: `if (adev->in_suspend &&
      !runpm_check) return -EBUSY;` (was `-EPERM`)
  - This function gates access in `amdgpu_pm_get_access()` and
    `amdgpu_pm_get_access_if_active()`:
    - `drivers/gpu/drm/amd/pm/amdgpu_pm.c:133`: `ret =
      amdgpu_pm_dev_state_check(adev, true);`
    - `drivers/gpu/drm/amd/pm/amdgpu_pm.c:153`: `ret =
      amdgpu_pm_dev_state_check(adev, false);`
  - Numerous PM-related sysfs show/store handlers directly return the
    `ret` from these helpers (e.g., `amdgpu_get_power_dpm_state()`
    returns `ret` on failure), so the errno visible to userspace changes
    from `-EPERM` to `-EBUSY` when the device is resetting or suspended
    (example call and return: `drivers/gpu/drm/amd/pm/amdgpu_pm.c:217`
    onward in the `amdgpu_get_power_dpm_state` path shows the pattern of
    `ret = ...; if (ret) return ret;`).

- Why it’s a bug fix suitable for stable
  - Correctness/semantics: `-EPERM` indicates a permissions problem,
    which is misleading here; the device is temporarily unavailable due
    to reset or suspend. `-EBUSY` accurately communicates a transient
    busy state and invites retry, which aligns better with userspace
    expectations and error handling.
  - Scope and risk: The change is tiny and localized to return codes in
    a single helper. It does not alter call sequences, state checks, PM
    flows, or locking. No ABI or uAPI additions, no
    structural/architectural changes.
  - Impacted surface: Only sysfs PM nodes’ errno in specific exceptional
    states. In-kernel callers are not affected (the helpers are
    `static`). Userspace seeing `-EBUSY` instead of `-EPERM` is an
    improvement for diagnostics and retry logic. AMDGPU already returns
    `-EBUSY` in analogous busy conditions elsewhere, so this aligns with
    existing patterns.
  - Stability: No performance, functional, or security regression
    vectors are introduced. The remaining `-EPERM` usage in
    `amdgpu_pm_get_access_if_active()` when the device is not active
    (`drivers/gpu/drm/amd/pm/amdgpu_pm.c:163`) is untouched, keeping
    behavior consistent for that distinct case.

- Backport considerations
  - The patch is self-contained and minimal. If the target stable trees
    already have `amdgpu_pm_dev_state_check()` and the access helpers,
    this applies cleanly. If older trees did the checks inline in each
    sysfs op, the backport would require equivalent one-line
    replacements at those sites; still trivial and low risk.
  - No user-visible feature change; only corrected errno in exceptional
    conditions, which is a common and acceptable class of stable fixes.

Given the small, precise nature of the change, its correctness benefit,
and minimal regression risk, this is a good candidate for stable
backporting.

 drivers/gpu/drm/amd/pm/amdgpu_pm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/pm/amdgpu_pm.c b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
index 5fbfe7333b54d..1fca183827c7c 100644
--- a/drivers/gpu/drm/amd/pm/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
@@ -110,9 +110,10 @@ static int amdgpu_pm_dev_state_check(struct amdgpu_device *adev, bool runpm)
 	bool runpm_check = runpm ? adev->in_runpm : false;
 
 	if (amdgpu_in_reset(adev))
-		return -EPERM;
+		return -EBUSY;
+
 	if (adev->in_suspend && !runpm_check)
-		return -EPERM;
+		return -EBUSY;
 
 	return 0;
 }
-- 
2.51.0