gpu: host1x: Select context device based on attached IOMMU

On Tegra234, engines that are programmed through Host1x channels can
be attached to either the NISO0 or NISO1 SMMU. Because of that, when
selecting a context device to use with an engine, we need to select
one that is also attached to the same SMMU.

Add a parameter to host1x_memory_context_alloc to specify which device
we are allocating a context for, and use it to pick an appropriate
context device.
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
[treding@nvidia.com: update !IOMMU_API stub signature]
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/uapi.c

@@ -116,7 +116,7 @@ int tegra_drm_ioctl_channel_open(struct drm_device *drm, void *data, struct drm_
 
 		if (supported)
 			context->memory_context = host1x_memory_context_alloc(
-				host, get_task_pid(current, PIDTYPE_TGID));
+				host, client->base.dev, get_task_pid(current, PIDTYPE_TGID));
 
 		if (IS_ERR(context->memory_context)) {
 			if (PTR_ERR(context->memory_context) != -EOPNOTSUPP) {

drivers/gpu/host1x/context.c

@@ -104,6 +104,7 @@ void host1x_memory_context_list_free(struct host1x_memory_context_list *cdl)
 }
 
 struct host1x_memory_context *host1x_memory_context_alloc(struct host1x *host1x,
+							  struct device *dev,
 							  struct pid *pid)
 {
 	struct host1x_memory_context_list *cdl = &host1x->context_list;
@@ -118,6 +119,9 @@ struct host1x_memory_context *host1x_memory_context_alloc(struct host1x *host1x,
 	for (i = 0; i < cdl->len; i++) {
 		struct host1x_memory_context *cd = &cdl->devs[i];
 
+		if (cd->dev.iommu->iommu_dev != dev->iommu->iommu_dev)
+			continue;
+
 		if (cd->owner == pid) {
 			refcount_inc(&cd->ref);
 			mutex_unlock(&cdl->lock);

include/linux/host1x.h

@@ -469,11 +469,13 @@ struct host1x_memory_context {
 
 #ifdef CONFIG_IOMMU_API
 struct host1x_memory_context *host1x_memory_context_alloc(struct host1x *host1x,
+							  struct device *dev,
 							  struct pid *pid);
 void host1x_memory_context_get(struct host1x_memory_context *cd);
 void host1x_memory_context_put(struct host1x_memory_context *cd);
 #else
 static inline struct host1x_memory_context *host1x_memory_context_alloc(struct host1x *host1x,
+									struct device *dev,
 									struct pid *pid)
 {
 	return NULL;