[PATCH v5 12/20] drm/nouveau/kms: Only use hpd_work for reprobing in HPD paths

Lyude Paul
2020-08-26T18:27:52Z

Currently we perform both short IRQ handling for DP, and connector
reprobing in the HPD IRQ handler. However since we need to grab
connection_mutex in order to reprobe a connector, in theory we could
accidentally block ourselves from handling any short IRQs until after a
modeset completes if a connector hotplug happens to occur in parallel
with a modeset.

I haven't seen this actually happen yet, but since we're cleaning up
nouveau's hotplug handling code anyway and we already have a hpd worker,
we can simply fix this by only relying on the HPD worker to actually
reprobe connectors when we receive a HPD IRQ. We also add a mask to
nouveau_drm to keep track of which connectors are waiting to be reprobed
in response to an HPD IRQ.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
---
drivers/gpu/drm/nouveau/nouveau_connector.c | 42 +++++--------
drivers/gpu/drm/nouveau/nouveau_connector.h | 1 +
drivers/gpu/drm/nouveau/nouveau_display.c | 70 ++++++++++++++++++---
drivers/gpu/drm/nouveau/nouveau_display.h | 1 +
drivers/gpu/drm/nouveau/nouveau_dp.c | 2 +-
drivers/gpu/drm/nouveau/nouveau_drm.c | 4 +-
drivers/gpu/drm/nouveau/nouveau_drv.h | 2 +
7 files changed, 86 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 4a29f691c08e4..637e91594fbe8 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -1138,6 +1138,20 @@ nouveau_connector_funcs_lvds = {
.early_unregister = nouveau_connector_early_unregister,
};

+void
+nouveau_connector_hpd(struct drm_connector *connector)
+{
+ struct nouveau_drm *drm = nouveau_drm(connector->dev);
+ u32 mask = drm_connector_mask(connector);
+
+ mutex_lock(&drm->hpd_lock);
+ if (!(drm->hpd_pending & mask)) {
+ drm->hpd_pending |= mask;
+ schedule_work(&drm->hpd_work);
+ }
+ mutex_unlock(&drm->hpd_lock);
+}
+
static int
nouveau_connector_hotplug(struct nvif_notify *notify)
{
@@ -1147,8 +1161,6 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
struct drm_device *dev = connector->dev;
struct nouveau_drm *drm = nouveau_drm(dev);
const struct nvif_notify_conn_rep_v0 *rep = notify->data;
- const char *name = connector->name;
- int ret;
bool plugged = (rep->mask != NVIF_NOTIFY_CONN_V0_UNPLUG);

if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) {
@@ -1156,31 +1168,9 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
return NVIF_NOTIFY_KEEP;
}

- ret = pm_runtime_get(drm->dev->dev);
- if (ret == 0) {
- /* We can't block here if there's a pending PM request
- * running, as we'll deadlock nouveau_display_fini() when it
- * calls nvif_put() on our nvif_notify struct. So, simply
- * defer the hotplug event until the device finishes resuming
- */
- NV_DEBUG(drm, "Deferring HPD on %s until runtime resume\n",
- name);
- schedule_work(&drm->hpd_work);
-
- pm_runtime_put_noidle(drm->dev->dev);
- return NVIF_NOTIFY_KEEP;
- } else if (ret != 1 && ret != -EACCES) {
- NV_WARN(drm, "HPD on %s dropped due to RPM failure: %d\n",
- name, ret);
- return NVIF_NOTIFY_DROP;
- }
-
- NV_DEBUG(drm, "%splugged %s\n", plugged ? "" : "un", name);
-
- drm_helper_hpd_irq_event(connector->dev);
+ NV_DEBUG(drm, "%splugged %s\n", plugged ? "" : "un", connector->name);
+ nouveau_connector_hpd(connector);

- pm_runtime_mark_last_busy(drm->dev->dev);
- pm_runtime_put_autosuspend(drm->dev->dev);
return NVIF_NOTIFY_KEEP;
}

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.h b/drivers/gpu/drm/nouveau/nouveau_connector.h
index d6de5cb8e2238..d0b859c4a80ea 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.h
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.h
@@ -187,6 +187,7 @@ nouveau_crtc_connector_get(struct nouveau_crtc *nv_crtc)

struct drm_connector *
nouveau_connector_create(struct drm_device *, const struct dcb_output *);
+void nouveau_connector_hpd(struct drm_connector *connector);

extern int nouveau_tv_disable;
extern int nouveau_ignorelid;
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index 13016769a194b..bceb48a2dfca6 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -457,16 +457,70 @@ static struct nouveau_drm_prop_enum_list dither_depth[] = {
} \
} while(0)

+void
+nouveau_display_hpd_resume(struct drm_device *dev)
+{
+ struct nouveau_drm *drm = nouveau_drm(dev);
+
+ mutex_lock(&drm->hpd_lock);
+ drm->hpd_pending = ~0;
+ mutex_unlock(&drm->hpd_lock);
+
+ schedule_work(&drm->hpd_work);
+}
+
static void
nouveau_display_hpd_work(struct work_struct *work)
{
struct nouveau_drm *drm = container_of(work, typeof(*drm), hpd_work);
+ struct drm_device *dev = drm->dev;
+ struct drm_connector *connector;
+ struct drm_connector_list_iter conn_iter;
+ u32 pending;
+ bool changed = false;
+
+ pm_runtime_get_sync(dev->dev);

- pm_runtime_get_sync(drm->dev->dev);
+ mutex_lock(&drm->hpd_lock);
+ pending = drm->hpd_pending;
+ drm->hpd_pending = 0;
+ mutex_unlock(&drm->hpd_lock);

- drm_helper_hpd_irq_event(drm->dev);
+ /* Nothing to do, exit early without updating the last busy counter */
+ if (!pending)
+ goto noop;
+
+ mutex_lock(&dev->mode_config.mutex);
+ drm_connector_list_iter_begin(dev, &conn_iter);
+
+ nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {
+ enum drm_connector_status old_status = connector->status;
+ u64 old_epoch_counter = connector->epoch_counter;
+
+ if (!(pending & drm_connector_mask(connector)))
+ continue;
+
+ connector->status = drm_helper_probe_detect(connector, NULL,
+ false);
+ if (old_epoch_counter == connector->epoch_counter)
+ continue;
+
+ changed = true;
+ drm_dbg_kms(dev, "[CONNECTOR:%d:%s] status updated from %s to %s (epoch counter %llu->%llu)\n",
+ connector->base.id, connector->name,
+ drm_get_connector_status_name(old_status),
+ drm_get_connector_status_name(connector->status),
+ old_epoch_counter, connector->epoch_counter);
+ }
+
+ drm_connector_list_iter_end(&conn_iter);
+ mutex_unlock(&dev->mode_config.mutex);
+
+ if (changed)
+ drm_kms_helper_hotplug_event(dev);

pm_runtime_mark_last_busy(drm->dev->dev);
+noop:
pm_runtime_put_sync(drm->dev->dev);
}

@@ -490,12 +544,11 @@ nouveau_display_acpi_ntfy(struct notifier_block *nb, unsigned long val,
*/
pm_runtime_put_autosuspend(drm->dev->dev);
} else if (ret == 0) {
- /* This may be the only indication we receive
- * of a connector hotplug on a runtime
- * suspended GPU, schedule hpd_work to check.
+ /* We've started resuming the GPU already, so
+ * it will handle scheduling a full reprobe
+ * itself
*/
NV_DEBUG(drm, "ACPI requested connector reprobe\n");
- schedule_work(&drm->hpd_work);
pm_runtime_put_noidle(drm->dev->dev);
} else {
NV_WARN(drm, "Dropped ACPI reprobe event due to RPM error: %d\n",
@@ -686,6 +739,7 @@ nouveau_display_create(struct drm_device *dev)
}

INIT_WORK(&drm->hpd_work, nouveau_display_hpd_work);
+ mutex_init(&drm->hpd_lock);
#ifdef CONFIG_ACPI
drm->acpi_nb.notifier_call = nouveau_display_acpi_ntfy;
register_acpi_notifier(&drm->acpi_nb);
@@ -705,9 +759,10 @@ void
nouveau_display_destroy(struct drm_device *dev)
{
struct nouveau_display *disp = nouveau_display(dev);
+ struct nouveau_drm *drm = nouveau_drm(dev);

#ifdef CONFIG_ACPI
- unregister_acpi_notifier(&nouveau_drm(dev)->acpi_nb);
+ unregister_acpi_notifier(&drm->acpi_nb);
#endif

drm_kms_helper_poll_fini(dev);
@@ -719,6 +774,7 @@ nouveau_display_destroy(struct drm_device *dev)
nvif_disp_dtor(&disp->disp);

nouveau_drm(dev)->display = NULL;
+ mutex_destroy(&drm->hpd_lock);
kfree(disp);
}

diff --git a/drivers/gpu/drm/nouveau/nouveau_display.h b/drivers/gpu/drm/nouveau/nouveau_display.h
index 76ba93e01aff4..616c434270594 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.h
+++ b/drivers/gpu/drm/nouveau/nouveau_display.h
@@ -45,6 +45,7 @@ nouveau_display(struct drm_device *dev)
int nouveau_display_create(struct drm_device *dev);
void nouveau_display_destroy(struct drm_device *dev);
int nouveau_display_init(struct drm_device *dev, bool resume, bool runtime);
+void nouveau_display_hpd_resume(struct drm_device *dev);
void nouveau_display_fini(struct drm_device *dev, bool suspend, bool runtime);
int nouveau_display_suspend(struct drm_device *dev, bool runtime);
void nouveau_display_resume(struct drm_device *dev, bool runtime);
diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index a5934064a75ea..005750aeb6d4f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -165,7 +165,7 @@ void nouveau_dp_irq(struct nouveau_drm *drm,

if (mstm && mstm->is_mst) {
if (!nv50_mstm_service(drm, nv_connector, mstm))
- schedule_work(&drm->hpd_work);
+ nouveau_connector_hpd(connector);
} else {
drm_dp_cec_irq(&nv_connector->aux);
}
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 22d246acc5e52..42fc5c813a9bb 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -953,7 +953,7 @@ nouveau_pmops_resume(struct device *dev)
ret = nouveau_do_resume(drm_dev, false);

/* Monitors may have been connected / disconnected during suspend */
- schedule_work(&nouveau_drm(drm_dev)->hpd_work);
+ nouveau_display_hpd_resume(drm_dev);

return ret;
}
@@ -1036,7 +1036,7 @@ nouveau_pmops_runtime_resume(struct device *dev)
drm_dev->switch_power_state = DRM_SWITCH_POWER_ON;

/* Monitors may have been connected / disconnected during suspend */
- schedule_work(&nouveau_drm(drm_dev)->hpd_work);
+ nouveau_display_hpd_resume(drm_dev);

return ret;
}
diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
index f63ac72aa556f..73ebf5fba2fcd 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -198,6 +198,8 @@ struct nouveau_drm {
struct nvbios vbios;
struct nouveau_display *display;
struct work_struct hpd_work;
+ struct mutex hpd_lock;
+ u32 hpd_pending;
struct work_struct fbcon_work;
int fbcon_new_state;
#ifdef CONFIG_ACPI
--
2.26.2