[PATCH] drm/dp: add a hw mutex around the transfer functions.

[Dave Airlie <airlied@gmail.com>]

From: Dave Airlie <airlied@redhat.com>

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

Signed-off-by: Dave Airlie <airlied@redhat.com>
---
 drivers/gpu/drm/drm_dp_helper.c      | 15 +++++++++++++++
 drivers/gpu/drm/i915/intel_dp.c      |  1 +
 drivers/gpu/drm/radeon/atombios_dp.c |  2 ++
 drivers/gpu/drm/tegra/dpaux.c        |  1 +
 include/drm/drm_dp_helper.h          |  3 ++-
 5 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 494219c..cb687f4 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -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;
@@ -761,3 +766,13 @@ void drm_dp_aux_unregister_i2c_bus(struct drm_dp_aux *aux)
 	i2c_del_adapter(&aux->ddc);
 }
 EXPORT_SYMBOL(drm_dp_aux_unregister_i2c_bus);
+
+/**
+ * drm_dp_aux_init() - init a DP aux internal structure.
+ * @aux: DisplayPort AUX channel
+ */
+void drm_dp_aux_init(struct drm_dp_aux *aux)
+{
+	mutex_init(&aux->hw_mutex);
+}
+EXPORT_SYMBOL(drm_dp_aux_init);
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index c4d8839..aa99dcb 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -698,6 +698,7 @@ intel_dp_aux_init(struct intel_dp *intel_dp, struct intel_connector *connector)
 	intel_dp->aux.name = name;
 	intel_dp->aux.dev = dev->dev;
 	intel_dp->aux.transfer = intel_dp_aux_transfer;
+	drm_dp_aux_init(&intel_dp->aux);
 
 	DRM_DEBUG_KMS("registering %s bus for %s\n", name,
 		      connector->base.kdev->kobj.name);
diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 225f6c6..12d8784 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -222,6 +222,8 @@ 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;
+
+	drm_dp_aux_init(&radeon_connector->ddc_bus->aux);
 	ret = drm_dp_aux_register_i2c_bus(&radeon_connector->ddc_bus->aux);
 	if (!ret)
 		radeon_connector->ddc_bus->has_aux = true;
diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c
index 005c19b..98cd70b 100644
--- a/drivers/gpu/drm/tegra/dpaux.c
+++ b/drivers/gpu/drm/tegra/dpaux.c
@@ -331,6 +331,7 @@ static int tegra_dpaux_probe(struct platform_device *pdev)
 
 	dpaux->aux.transfer = tegra_dpaux_transfer;
 	dpaux->aux.dev = &pdev->dev;
+	drm_dp_aux_init(&dpaux->aux);
 
 	err = drm_dp_aux_register_i2c_bus(&dpaux->aux);
 	if (err < 0)
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 488b416..09eee36 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -546,7 +546,7 @@ struct drm_dp_aux {
 	const char *name;
 	struct i2c_adapter ddc;
 	struct device *dev;
-
+	struct mutex hw_mutex;
 	ssize_t (*transfer)(struct drm_dp_aux *aux,
 			    struct drm_dp_aux_msg *msg);
 };
@@ -607,5 +607,6 @@ int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link);
 
 int drm_dp_aux_register_i2c_bus(struct drm_dp_aux *aux);
 void drm_dp_aux_unregister_i2c_bus(struct drm_dp_aux *aux);
+void drm_dp_aux_init(struct drm_dp_aux *aux);
 
 #endif /* _DRM_DP_HELPER_H_ */
-- 
1.9.3