Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [High] drm/imagination: pvr_power_device_idle() bypasses idle check on autosuspend --
commit 21bc022f1187eccd547ba4f832837505cc945974 Author: Baihui Liang <[email protected]> drm/imagination: retry runtime idle when firmware is not yet idle This patch modifies pvr_power_device_idle() to call pm_runtime_autosuspend() before returning -EBUSY when pvr_power_is_idle() returns false, aiming to retry the idle check once the firmware reaches ROGUE_FWIF_POW_IDLE. > diff --git a/drivers/gpu/drm/imagination/pvr_power.c > b/drivers/gpu/drm/imagination/pvr_power.c > index eb4b6ecdf4f4d..6f38249ffcb72 100644 > --- a/drivers/gpu/drm/imagination/pvr_power.c > +++ b/drivers/gpu/drm/imagination/pvr_power.c > @@ -434,7 +434,16 @@ pvr_power_device_idle(struct device *dev) > struct drm_device *drm_dev = platform_get_drvdata(plat_dev); > struct pvr_device *pvr_dev = to_pvr_device(drm_dev); > > - return pvr_power_is_idle(pvr_dev) ? 0 : -EBUSY; > + if (pvr_power_is_idle(pvr_dev)) > + return 0; > + > + /* > + * Firmware not yet idle; reject but schedule autosuspend so > + * runtime_idle() can be retried. > + */ > + pm_runtime_autosuspend(dev); > + > + return -EBUSY; > } [Severity: High] Does calling pm_runtime_autosuspend() from pvr_power_device_idle() actually retry the ->runtime_idle() callback, or does it bypass the idle check and run pvr_power_device_suspend() directly? Looking at pm_runtime_autosuspend() in include/linux/pm_runtime.h: static inline int pm_runtime_autosuspend(struct device *dev) { pm_runtime_mark_last_busy(dev); return __pm_runtime_suspend(dev, RPM_AUTO); } When pvr_power_device_idle() calls pm_runtime_autosuspend() because pvr_power_is_idle() returned false (for example, when pvr_kccb_send_cmd() in drivers/gpu/drm/imagination/pvr_ccb.c drops its runtime PM reference via pvr_power_put() while a caller is still waiting in pvr_kccb_wait_for_completion(), or while firmware has not yet transitioned to ROGUE_FWIF_POW_IDLE), __pm_runtime_suspend(dev, RPM_AUTO) invokes rpm_suspend(dev, RPM_AUTO). When the autosuspend delay is non-zero, rpm_suspend() arms dev->power.suspend_timer with dev->power.timer_autosuspends = 1, and returning -EBUSY from pvr_power_device_idle() to rpm_idle() does not cancel that timer. When the timer fires, pm_suspend_timer_fn() in drivers/base/power/runtime.c runs: if (expires > 0 && expires <= ktime_get_mono_fast_ns()) { dev->power.timer_expires = 0; rpm_suspend(dev, dev->power.timer_autosuspends ? (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC); } This queues RPM_REQ_AUTOSUSPEND on pm_wq, which calls rpm_suspend() -> pvr_power_device_suspend() directly without calling rpm_idle() or pvr_power_device_idle(). Because pvr_power_device_suspend() in drivers/gpu/drm/imagination/pvr_power.c does not check pvr_power_is_idle(): int pvr_power_device_suspend(struct device *dev) { ... if (READ_ONCE(pvr_dev->fw_dev.initialised)) { err = pvr_power_fw_disable(pvr_dev, false, true); won't the driver unconditionally disable firmware when the autosuspend timer expires, even if the firmware or KCCB is still busy? Furthermore, if pm_runtime_autosuspend_expiration() returns 0 when pm_runtime_autosuspend() is called (for example, if autosuspend_delay_ms is set to 0 via sysfs), __pm_runtime_suspend(dev, RPM_AUTO) is synchronous and will execute pvr_power_device_suspend() immediately from inside pvr_power_device_idle() right after pvr_power_is_idle() returned false. -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=1
