[PATCH 1/1] PM: runtime: change stub pm_runtime_get_if_active() return 1 when !CONFIG_PM

[Frank.Li at oss.nxp.com]

From: Frank Li <Frank.Li at nxp.com>

When CONFIG_PM is not enabled, all devices runtime PM state should be
treated as active.

__pm_runtime_resume() returns 1 (called by pm_runtime_get()).
pm_runtime_get_if_active() is the try-and-get version of pm_runtime_get().
stub pm_runtime_active() also returns true. So pm_runtime_get_if_active()
should return the same value as the stub pm_runtime_get(), which is 1.

Analysis of all callers and their behavior with old (-EINVAL) vs new (1):

Pattern A: if (!pm_runtime_get_if_active(dev)) -- no impact
  Both -EINVAL and 1 are non-zero, so !ret is false in both cases.
  Callers: drivers/accel/ethosu/ethosu_perfmon.c,
           drivers/gpu/drm/msm/adreno/a6xx_gmu.c,
           drivers/gpu/drm/msm/msm_perfcntr.c,
           drivers/gpu/drm/v3d/v3d_mmu.c,
           drivers/gpu/drm/v3d/v3d_perfmon.c (x4),
           drivers/media/i2c/gc08a3.c gc05a2.c og0ve1b.c ov6211.c,
           drivers/media/i2c/ccs/ccs-core.c s5kjn1.c lm3560.c (x2),
           drivers/media/i2c/s5k3m5.c thp7312.c imx283.c ov64a40.c,
           drivers/media/pci/intel/ipu6/ipu6-buttress.c,
           sound/hda/core/device.c

Pattern B: if (!ret) after get -- no impact
  Both -EINVAL and 1 are non-zero, !ret is false in both cases.
  drivers/gpu/drm/amd/pm/amdgpu_pm.c (comment says "allow access"
    in kernels without CONFIG_PM), drivers/pci/pci.c

Pattern C: ret > 0 / ret <= 0 / ret != 1 checks -- FIXED
  drivers/usb/core/offload.c: checks (!= 1), old -EINVAL caused
    -EBUSY even with !CONFIG_PM. Fixed: now returns 1, proceeds.
  drivers/accel/ivpu/ivpu_job.c: drm_WARN_ON(<= 0), old -EINVAL
    spuriously triggered WARN. Fixed: 1 > 0, no warn.
  drivers/gpu/drm/i915/intel_runtime_pm.c: checks (<= 0), old
    -EINVAL triggered error path. Fixed: 1 > 0, correct path.
  drivers/accel/ivpu/ivpu_sysfs.c: (> 0), old skipped freq read.
    Fixed: proceeds correctly without CONFIG_PM.
  drivers/gpu/drm/xe/xe_pm.c: wraps (> 0), all xe callers
    (xe_bo.c, xe_shrinker.c, xe_vsec.c, xe_ggtt.c, xe_guc_ct.c,
    xe_pxp.c) now correctly treat !CONFIG_PM as active.
  drivers/net/ipa/ipa_smp2p.c: power_on = (> 0), now correctly true.
  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c: (> 0), now correctly
    executes stall register update.
  drivers/staging/media/ipu7/ipu7-buttress.c: active (<= 0) early
    return now skipped, correctly proceeds.

Pattern D: explicit -EINVAL check
  drivers/hwmon/prom21-xhci.c: checks (> 0) then (== -EINVAL).
    Old: took -EINVAL fallback. New: takes (> 0) fast path.
    Both succeed when CONFIG_PM is disabled; functionally equivalent.
  drivers/hwmon/eic7700-pvt.c: call is guarded by IS_ENABLED(CONFIG_PM),
    stub is never reached. No impact.

Signed-off-by: Frank Li <Frank.Li at nxp.com>
---
Cc: "Rafael J. Wysocki" <rafael at kernel.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Andrzej Kacprowski <andrzej.kacprowski at linux.intel.com>
Cc: Karol Wachowski <karol.wachowski at linux.intel.com>
Cc: Oded Gabbay <ogabbay at kernel.org>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Tvrtko Ursulin <tursulin at ursulin.net>
Cc: Matthew Brost <matthew.brost at intel.com>
Cc: "Thomas Hellstrom" <thomas.hellstrom at linux.intel.com>
Cc: David Airlie <airlied at gmail.com>
Cc: Simona Vetter <simona at ffwll.ch>
Cc: Alex Elder <elder at kernel.org>
Cc: Will Deacon <will at kernel.org>
Cc: Robin Murphy <robin.murphy at arm.com>
Cc: "Joerg Roedel" <joro at 8bytes.org>
Cc: Rob Clark <robin.clark at oss.qualcomm.com>
Cc: Sakari Ailus <sakari.ailus at linux.intel.com>
Cc: Mauro Carvalho Chehab <mchehab at kernel.org>
Cc: Guenter Roeck <linux at roeck-us.net>
Cc: Guan-Yu Lin <guanyulin at google.com>
Cc: Mathias Nyman <mathias.nyman at linux.intel.com>
Cc: linux-pm at vger.kernel.org
Cc: linux-usb at vger.kernel.org
Cc: dri-devel at lists.freedesktop.org
Cc: intel-gfx at lists.freedesktop.org
Cc: intel-xe at lists.freedesktop.org
Cc: linux-hwmon at vger.kernel.org
Cc: linux-arm-kernel at lists.infradead.org
Cc: iommu at lists.linux.dev
Cc: linux-arm-msm at vger.kernel.org
Cc: linux-media at vger.kernel.org
Cc: linux-staging at lists.linux.dev
Cc: netdev at vger.kernel.org
Cc: imx at lists.linux.dev
Cc: Rob Herring (Arm) <robh at kernel.org>
---
 include/linux/pm_runtime.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index 64921b10ac74f..de9e7518ecef2 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -280,7 +280,7 @@ static inline int pm_runtime_get_if_in_use(struct device *dev)
 }
 static inline int pm_runtime_get_if_active(struct device *dev)
 {
-	return -EINVAL;
+	return 1;
 }
 static inline int __pm_runtime_set_status(struct device *dev,
 					    unsigned int status) { return 0; }
-- 
2.43.0