drm/dp: add a hw mutex around the transfer functions. (v2)

This should avoid races between connector probing and HPD
irqs in the future, currently mode_config.mutex blocks this
possibility.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

6 files changed, 29 insertions, 20 deletions

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 494219ccdf96..08e33b8b13a4 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -216,7 +216,7 @@ i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter)
  *
  * IMPORTANT:
  * This interface is deprecated, please switch to the new dp aux helpers and
- * drm_dp_aux_register_i2c_bus().
+ * drm_dp_aux_register().
  */
 int
 i2c_dp_aux_add_bus(struct i2c_adapter *adapter)
@@ -382,7 +382,10 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
          * transactions.
          */
         for (retry = 0; retry < 7; retry++) {
+
+                mutex_lock(&aux->hw_mutex);
                 err = aux->transfer(aux, &msg);
+                mutex_unlock(&aux->hw_mutex);
                 if (err < 0) {
                         if (err == -EBUSY)
                                 continue;
@@ -596,7 +599,9 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
          * before giving up the AUX transaction.
          */
         for (retry = 0; retry < 7; retry++) {
+                mutex_lock(&aux->hw_mutex);
                 err = aux->transfer(aux, msg);
+                mutex_unlock(&aux->hw_mutex);
                 if (err < 0) {
                         if (err == -EBUSY)
                                 continue;
@@ -729,13 +734,15 @@ static const struct i2c_algorithm drm_dp_i2c_algo = {
 };
 
 /**
- * drm_dp_aux_register_i2c_bus() - register an I2C adapter for I2C-over-AUX
+ * drm_dp_aux_register() - initialise and register aux channel
  * @aux: DisplayPort AUX channel
  *
  * Returns 0 on success or a negative error code on failure.
  */
-int drm_dp_aux_register_i2c_bus(struct drm_dp_aux *aux)
+int drm_dp_aux_register(struct drm_dp_aux *aux)
 {
+        mutex_init(&aux->hw_mutex);
+
         aux->ddc.algo = &drm_dp_i2c_algo;
         aux->ddc.algo_data = aux;
         aux->ddc.retries = 3;
@@ -750,14 +757,14 @@ int drm_dp_aux_register_i2c_bus(struct drm_dp_aux *aux)
 
         return i2c_add_adapter(&aux->ddc);
 }
-EXPORT_SYMBOL(drm_dp_aux_register_i2c_bus);
+EXPORT_SYMBOL(drm_dp_aux_register);
 
 /**
- * drm_dp_aux_unregister_i2c_bus() - unregister an I2C-over-AUX adapter
+ * drm_dp_aux_unregister() - unregister an AUX adapter
  * @aux: DisplayPort AUX channel
  */
-void drm_dp_aux_unregister_i2c_bus(struct drm_dp_aux *aux)
+void drm_dp_aux_unregister(struct drm_dp_aux *aux)
 {
         i2c_del_adapter(&aux->ddc);
 }
-EXPORT_SYMBOL(drm_dp_aux_unregister_i2c_bus);
+EXPORT_SYMBOL(drm_dp_aux_unregister);
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index c4d883921282..d01bb430b5bc 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -702,9 +702,9 @@ intel_dp_aux_init(struct intel_dp *intel_dp, struct intel_connector *connector)
         DRM_DEBUG_KMS("registering %s bus for %s\n", name,
                       connector->base.kdev->kobj.name);
 
-        ret = drm_dp_aux_register_i2c_bus(&intel_dp->aux);
+        ret = drm_dp_aux_register(&intel_dp->aux);
         if (ret < 0) {
-                DRM_ERROR("drm_dp_aux_register_i2c_bus() for %s failed (%d)\n",
+                DRM_ERROR("drm_dp_aux_register() for %s failed (%d)\n",
                           name, ret);
                 return;
         }
@@ -714,7 +714,7 @@ intel_dp_aux_init(struct intel_dp *intel_dp, struct intel_connector *connector)
                                 intel_dp->aux.ddc.dev.kobj.name);
         if (ret < 0) {
                 DRM_ERROR("sysfs_create_link() for %s failed (%d)\n", name, ret);
-                drm_dp_aux_unregister_i2c_bus(&intel_dp->aux);
+                drm_dp_aux_unregister(&intel_dp->aux);
         }
 }
 
@@ -3662,7 +3662,7 @@ void intel_dp_encoder_destroy(struct drm_encoder *encoder)
         struct intel_dp *intel_dp = &intel_dig_port->dp;
         struct drm_device *dev = intel_dp_to_dev(intel_dp);
 
-        drm_dp_aux_unregister_i2c_bus(&intel_dp->aux);
+        drm_dp_aux_unregister(&intel_dp->aux);
         drm_encoder_cleanup(encoder);
         if (is_edp(intel_dp)) {
                 cancel_delayed_work_sync(&intel_dp->panel_vdd_work);
@@ -4244,7 +4244,7 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
         intel_dp->psr_setup_done = false;
 
         if (!intel_edp_init_connector(intel_dp, intel_connector, &power_seq)) {
-                drm_dp_aux_unregister_i2c_bus(&intel_dp->aux);
+                drm_dp_aux_unregister(&intel_dp->aux);
                 if (is_edp(intel_dp)) {
                         cancel_delayed_work_sync(&intel_dp->panel_vdd_work);
                         mutex_lock(&dev->mode_config.connection_mutex);
diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 225f6c66effa..a54c44181a0f 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -222,11 +222,12 @@ void radeon_dp_aux_init(struct radeon_connector *radeon_connector)
         radeon_connector->ddc_bus->rec.hpd = radeon_connector->hpd.hpd;
         radeon_connector->ddc_bus->aux.dev = radeon_connector->base.kdev;
         radeon_connector->ddc_bus->aux.transfer = radeon_dp_aux_transfer;
-        ret = drm_dp_aux_register_i2c_bus(&radeon_connector->ddc_bus->aux);
+
+        ret = drm_dp_aux_register(&radeon_connector->ddc_bus->aux);
         if (!ret)
                 radeon_connector->ddc_bus->has_aux = true;
 
-        WARN(ret, "drm_dp_aux_register_i2c_bus() failed with error %d\n", ret);
+        WARN(ret, "drm_dp_aux_register() failed with error %d\n", ret);
 }
 
 /***** general DP utility functions *****/
diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
index 427ee4d6d0b5..add622008407 100644
--- a/drivers/gpu/drm/radeon/radeon_i2c.c
+++ b/drivers/gpu/drm/radeon/radeon_i2c.c
@@ -988,7 +988,7 @@ void radeon_i2c_destroy(struct radeon_i2c_chan *i2c)
                 return;
         i2c_del_adapter(&i2c->adapter);
         if (i2c->has_aux)
-                drm_dp_aux_unregister_i2c_bus(&i2c->aux);
+                drm_dp_aux_unregister(&i2c->aux);
         kfree(i2c);
 }
 
diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c
index 005c19bd92df..2b725ba7facc 100644
--- a/drivers/gpu/drm/tegra/dpaux.c
+++ b/drivers/gpu/drm/tegra/dpaux.c
@@ -332,7 +332,7 @@ static int tegra_dpaux_probe(struct platform_device *pdev)
         dpaux->aux.transfer = tegra_dpaux_transfer;
         dpaux->aux.dev = &pdev->dev;