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Commit 3846fd9b authored by Daniel Vetter's avatar Daniel Vetter
Browse files

drm/probe-helpers: Drop locking from poll_enable 



It was only needed to protect the connector_list walking, see

commit 8c4ccc4a
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
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 c36a3254
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
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 <airlied@gmail.com>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: default avatarLyude <lyude@redhat.com>
Reviewed-by: default avatarLyude <lyude@redhat.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170111090117.5134-1-daniel.vetter@ffwll.ch
parent fdf35a6b

drivers/gpu/drm/drm_probe_helper.c

+20 −31
Original line number Diff line number Diff line
@@ -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 @@ static void output_poll_execute(struct work_struct *work) 
 * 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

drivers/gpu/drm/i915/intel_hotplug.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

include/drm/drm_crtc_helper.h

+0 −1
Original line number Diff line number Diff line
@@ -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