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drm/probe-helpers: Drop locking from poll_enable

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It was only needed to protect the connector_list walking, see

commit 8c4ccc4ab6
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 c36a3254f7
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: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Lyude <lyude@redhat.com>
Reviewed-by: Lyude <lyude@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170111090117.5134-1-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter 2017-01-11 10:01:17 +01:00
parent fdf35a6b22
commit 3846fd9b86
3 changed files with 22 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
drivers/gpu/drm/drm_probe_helper.c
View File

@ -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

4
drivers/gpu/drm/i915/intel_hotplug.c
View File

@ -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);

1
include/drm/drm_crtc_helper.h
View File

@ -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