5 files changed, 51 insertions, 10 deletions

diff --git a/drivers/video/tegra/host/chip_support.h b/drivers/video/tegra/host/chip_support.h
index 23fcf6f39..1fcd53c15 100644
--- a/drivers/video/tegra/host/chip_support.h
+++ b/drivers/video/tegra/host/chip_support.h
@@ -65,7 +65,7 @@ struct nvhost_cdma_ops {
 };
 
 struct nvhost_vm_ops {
-        int (*init)(struct nvhost_vm *vm);
+        int (*init)(struct nvhost_vm *vm, void *identifier);
         void (*deinit)(struct nvhost_vm *vm);
         int (*pin_static_buffer)(struct platform_device *pdev,
                                  void *vaddr, dma_addr_t paddr,
diff --git a/drivers/video/tegra/host/host1x/host1x_vm_t186.c b/drivers/video/tegra/host/host1x/host1x_vm_t186.c
index 65f0742c6..c198ec84e 100644
--- a/drivers/video/tegra/host/host1x/host1x_vm_t186.c
+++ b/drivers/video/tegra/host/host1x/host1x_vm_t186.c
@@ -27,14 +27,14 @@
 /* 5 second timeout */
 #define NVHOST_VM_WAIT_TIMEOUT (5000)
 
-static int host1x_vm_init(struct nvhost_vm *vm)
+static int host1x_vm_init(struct nvhost_vm *vm, void *identifier)
 {
         struct platform_device *pdev;
         unsigned int i = 0;
 
         /* wait until we have a context device */
         do {
-                pdev = iommu_context_dev_allocate();
+                pdev = iommu_context_dev_allocate(identifier);
                 if (!pdev) {
                         ++i;
                         mdelay(1);
diff --git a/drivers/video/tegra/host/iommu_context_dev.c b/drivers/video/tegra/host/iommu_context_dev.c
index ead02e9dd..af9de61f3 100644
--- a/drivers/video/tegra/host/iommu_context_dev.c
+++ b/drivers/video/tegra/host/iommu_context_dev.c
@@ -47,24 +47,65 @@ struct iommu_ctx {
         struct list_head list;
         struct device_dma_parameters dma_parms;
         bool allocated;
+        void *prev_identifier;
 };
 
 static LIST_HEAD(iommu_ctx_list);
 static LIST_HEAD(iommu_static_mappings_list);
 static DEFINE_MUTEX(iommu_ctx_list_mutex);
 
-struct platform_device *iommu_context_dev_allocate(void)
+struct platform_device *iommu_context_dev_allocate(void *identifier)
 {
-        struct iommu_ctx *ctx;
+        struct iommu_ctx *ctx, *ctx_new = NULL;
+        bool dirty = false;
 
         mutex_lock(&iommu_ctx_list_mutex);
+        /*
+         * First check if we have same identifier stashed into
+         * some context device
+         * If yes, use that context device since it will have all
+         * the mappings stashed too
+         */
         list_for_each_entry(ctx, &iommu_ctx_list, list) {
-                if (!ctx->allocated) {
+                if (!ctx->allocated && identifier == ctx->prev_identifier) {
                         ctx->allocated = true;
                         mutex_unlock(&iommu_ctx_list_mutex);
                         return ctx->pdev;
                 }
         }
+
+        /*
+         * Otherwise, find a device which does not have any identifier stashed
+         * If there is no device left without identifier stashed, use any of
+         * the free device and explicitly remove all the stashings from it
+         */
+        list_for_each_entry(ctx, &iommu_ctx_list, list) {
+                if (!ctx->allocated && !ctx_new) {
+                        ctx_new = ctx;
+                        dirty = true;
+                }
+                if (!ctx->allocated && !ctx->prev_identifier) {
+                        ctx_new = ctx;
+                        dirty = false;
+                        break;
+                }
+        }
+
+        if (ctx_new) {
+                if (dirty) {
+                        /*
+                         * Ensure that all stashed mappings are removed from this context device
+                         * before this context device gets reassigned to some other process
+                         */
+                        dma_buf_release_stash(&ctx_new->pdev->dev);
+                }
+
+                ctx_new->prev_identifier = identifier;
+                ctx_new->allocated = true;
+                mutex_unlock(&iommu_ctx_list_mutex);
+                return ctx_new->pdev;
+        }
+
         mutex_unlock(&iommu_ctx_list_mutex);
 
         return NULL;
@@ -200,8 +241,8 @@ static int iommu_context_dev_probe(struct platform_device *pdev)
         pdev->dev.dma_parms = &ctx->dma_parms;
         dma_set_max_seg_size(&pdev->dev, UINT_MAX);
 
-        /* disable lazy unmapping for context devices */
-        dma_buf_disable_lazy_unmapping(&pdev->dev);
+        /* flag required to handle stashings in context devices */
+        pdev->dev.context_dev = true;
 
         dev_info(&pdev->dev, "initialized (streamid=%d)",
                  iommu_get_hwid(pdev->dev.archdata.iommu, &pdev->dev, 0));
diff --git a/drivers/video/tegra/host/iommu_context_dev.h b/drivers/video/tegra/host/iommu_context_dev.h
index e219265c2..9f0f40519 100644
--- a/drivers/video/tegra/host/iommu_context_dev.h
+++ b/drivers/video/tegra/host/iommu_context_dev.h
@@ -19,7 +19,7 @@
 #ifndef IOMMU_CONTEXT_DEV_H
 #define IOMMU_CONTEXT_DEV_H
 
-struct platform_device *iommu_context_dev_allocate(void);
+struct platform_device *iommu_context_dev_allocate(void *identifier);
 void iommu_context_dev_release(struct platform_device *pdev);
 int iommu_context_dev_get_streamid(struct platform_device *pdev);
 int iommu_context_dev_map_static(void *vaddr, dma_addr_t paddr, size_t size);
diff --git a/drivers/video/tegra/host/nvhost_vm.c b/drivers/video/tegra/host/nvhost_vm.c
index aaa03eb9b..979bb31fd 100644
--- a/drivers/video/tegra/host/nvhost_vm.c
+++ b/drivers/video/tegra/host/nvhost_vm.c
@@ -224,7 +224,7 @@ struct nvhost_vm *nvhost_vm_allocate(struct platform_device *pdev,
         mutex_unlock(&host->vm_mutex);
 
         if (vm_op().init && vm->enable_hw) {
-                err = vm_op().init(vm);
+                err = vm_op().init(vm, identifier);
                 if (err)
                         goto err_init;
         }