On 09/11/2018 07:43 AM, Noralf Trønnes wrote:
This adds a library for shmem backed GEM objects with the necessary
drm_driver callbacks.
Signed-off-by: Noralf Trønnes <nor...@tronnes.org>
---
...
+static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
+{
+ struct drm_gem_object *obj = &shmem->base;
+ int ret;
+
+ if (shmem->vmap_use_count++ > 0)
+ return 0;
+
+ ret = drm_gem_shmem_get_pages(shmem);
+ if (ret)
+ goto err_zero_use;
+
+ if (obj->import_attach) {
+ shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
+ } else {
+ pgprot_t prot;
+
+ switch (shmem->cache_mode) {
+ case DRM_GEM_SHMEM_BO_UNKNOWN:
+ DRM_DEBUG_KMS("Can't vmap cache mode is unknown\n");
+ ret = -EINVAL;
+ goto err_put_pages;
+
+ case DRM_GEM_SHMEM_BO_WRITECOMBINED:
+ prot = pgprot_writecombine(PAGE_KERNEL);
+ break;
+
+ case DRM_GEM_SHMEM_BO_UNCACHED:
+ prot = pgprot_noncached(PAGE_KERNEL);
+ break;
+
+ case DRM_GEM_SHMEM_BO_CACHED:
+ prot = PAGE_KERNEL;
+ break;
+ }
+
+ shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
VM_MAP, prot);
I get a gcc warning here:
/home/david/work/ev3dev2/ev3dev-kernel/drivers/gpu/drm/drm_gem_shmem_helper.c:220:18:
warning: ‘prot’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT, VM_MAP, prot);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/david/work/ev3dev2/ev3dev-kernel/drivers/gpu/drm/drm_gem_shmem_helper.c:199:12:
note: ‘prot’ was declared here
pgprot_t prot;
^~~~
---
And since I am making a comment anyway, it is not clear to me
what BO means in the enum names. I didn't see any hints in the
doc comments either.
+ }
+
+ if (!shmem->vaddr) {
+ DRM_DEBUG_KMS("Failed to vmap pages\n");
+ ret = -ENOMEM;
+ goto err_put_pages;
+ }
+
+ return 0;
+
+err_put_pages:
+ drm_gem_shmem_put_pages(shmem);
+err_zero_use:
+ shmem->vmap_use_count = 0;
+
+ return ret;
+}
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