From 3846fd9b86001bea171943cc3bb9222cb6da6b42 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 11 Jan 2017 10:01:17 +0100 Subject: [PATCH] drm/probe-helpers: Drop locking from poll_enable It was only needed to protect the connector_list walking, see commit 8c4ccc4ab6f64e859d4ff8d7c02c2ed2e956e07f Author: Daniel Vetter Date: Thu Jul 9 23:44:26 2015 +0200 drm/probe-helper: Grab mode_config.mutex in poll_init/enable Unfortunately the commit message of that patch fails to mention that the new locking check was for the connector_list. But that requirement disappeared in commit c36a3254f7857f1ad9badbe3578ccc92be541a8e Author: Daniel Vetter Date: Thu Dec 15 16:58:43 2016 +0100 drm: Convert all helpers to drm_connector_list_iter and so we can drop this again. This fixes a locking inversion on nouveau, where the rpm code needs to re-enable. But in other places the rpm_get() calls are nested within the big modeset locks. While at it, also improve the kerneldoc for these two functions a notch. v2: Update the kerneldoc even more to explain that these functions can't be called concurrently, or bad things happen (Chris). Cc: Dave Airlie Reviewed-by: Chris Wilson Cc: Chris Wilson Tested-by: Lyude Reviewed-by: Lyude Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20170111090117.5134-1-daniel.vetter@ffwll.ch --- drivers/gpu/drm/drm_probe_helper.c | 51 +++++++++++----------------- drivers/gpu/drm/i915/intel_hotplug.c | 4 +-- include/drm/drm_crtc_helper.h | 1 - 3 files changed, 22 insertions(+), 34 deletions(-) diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c index cf8f0128c161..b452a7ccd84b 100644 --- a/drivers/gpu/drm/drm_probe_helper.c +++ b/drivers/gpu/drm/drm_probe_helper.c @@ -115,24 +115,27 @@ static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector) #define DRM_OUTPUT_POLL_PERIOD (10*HZ) /** - * drm_kms_helper_poll_enable_locked - re-enable output polling. + * drm_kms_helper_poll_enable - re-enable output polling. * @dev: drm_device * - * This function re-enables the output polling work without - * locking the mode_config mutex. + * This function re-enables the output polling work, after it has been + * temporarily disabled using drm_kms_helper_poll_disable(), for example over + * suspend/resume. * - * This is like drm_kms_helper_poll_enable() however it is to be - * called from a context where the mode_config mutex is locked - * already. + * Drivers can call this helper from their device resume implementation. It is + * an error to call this when the output polling support has not yet been set + * up. + * + * Note that calls to enable and disable polling must be strictly ordered, which + * is automatically the case when they're only call from suspend/resume + * callbacks. */ -void drm_kms_helper_poll_enable_locked(struct drm_device *dev) +void drm_kms_helper_poll_enable(struct drm_device *dev) { bool poll = false; struct drm_connector *connector; unsigned long delay = DRM_OUTPUT_POLL_PERIOD; - WARN_ON(!mutex_is_locked(&dev->mode_config.mutex)); - if (!dev->mode_config.poll_enabled || !drm_kms_helper_poll) return; @@ -160,7 +163,7 @@ void drm_kms_helper_poll_enable_locked(struct drm_device *dev) if (poll) schedule_delayed_work(&dev->mode_config.output_poll_work, delay); } -EXPORT_SYMBOL(drm_kms_helper_poll_enable_locked); +EXPORT_SYMBOL(drm_kms_helper_poll_enable); static enum drm_connector_status drm_connector_detect(struct drm_connector *connector, bool force) @@ -287,7 +290,7 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector, /* Re-enable polling in case the global poll config changed. */ if (drm_kms_helper_poll != dev->mode_config.poll_running) - drm_kms_helper_poll_enable_locked(dev); + drm_kms_helper_poll_enable(dev); dev->mode_config.poll_running = drm_kms_helper_poll; @@ -479,8 +482,12 @@ out: * This function disables the output polling work. * * Drivers can call this helper from their device suspend implementation. It is - * not an error to call this even when output polling isn't enabled or arlready - * disabled. + * not an error to call this even when output polling isn't enabled or already + * disabled. Polling is re-enabled by calling drm_kms_helper_poll_enable(). + * + * Note that calls to enable and disable polling must be strictly ordered, which + * is automatically the case when they're only call from suspend/resume + * callbacks. */ void drm_kms_helper_poll_disable(struct drm_device *dev) { @@ -490,24 +497,6 @@ void drm_kms_helper_poll_disable(struct drm_device *dev) } EXPORT_SYMBOL(drm_kms_helper_poll_disable); -/** - * drm_kms_helper_poll_enable - re-enable output polling. - * @dev: drm_device - * - * This function re-enables the output polling work. - * - * Drivers can call this helper from their device resume implementation. It is - * an error to call this when the output polling support has not yet been set - * up. - */ -void drm_kms_helper_poll_enable(struct drm_device *dev) -{ - mutex_lock(&dev->mode_config.mutex); - drm_kms_helper_poll_enable_locked(dev); - mutex_unlock(&dev->mode_config.mutex); -} -EXPORT_SYMBOL(drm_kms_helper_poll_enable); - /** * drm_kms_helper_poll_init - initialize and enable output polling * @dev: drm_device diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c index 3d546c019de0..b62e3f8ad415 100644 --- a/drivers/gpu/drm/i915/intel_hotplug.c +++ b/drivers/gpu/drm/i915/intel_hotplug.c @@ -180,7 +180,7 @@ static void intel_hpd_irq_storm_disable(struct drm_i915_private *dev_priv) /* Enable polling and queue hotplug re-enabling. */ if (hpd_disabled) { - drm_kms_helper_poll_enable_locked(dev); + drm_kms_helper_poll_enable(dev); mod_delayed_work(system_wq, &dev_priv->hotplug.reenable_work, msecs_to_jiffies(HPD_STORM_REENABLE_DELAY)); } @@ -511,7 +511,7 @@ static void i915_hpd_poll_init_work(struct work_struct *work) } if (enabled) - drm_kms_helper_poll_enable_locked(dev); + drm_kms_helper_poll_enable(dev); mutex_unlock(&dev->mode_config.mutex); diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h index 982c299e435a..d026f5017c33 100644 --- a/include/drm/drm_crtc_helper.h +++ b/include/drm/drm_crtc_helper.h @@ -73,6 +73,5 @@ extern void drm_kms_helper_hotplug_event(struct drm_device *dev); extern void drm_kms_helper_poll_disable(struct drm_device *dev); extern void drm_kms_helper_poll_enable(struct drm_device *dev); -extern void drm_kms_helper_poll_enable_locked(struct drm_device *dev); #endif -- 2.39.5