[RFC v2 1/1] drm: allow to use mmuless SoC
Benjamin Gaignard
benjamin.gaignard at linaro.org
Wed Nov 30 13:19:18 UTC 2016
Some SoC without MMU have display driver where a drm/kms driver
could be implemented.
Before doing such kind of thing drm/kms must allow to use mmuless
devices.
This patch propose to remove MMU configuration flag and add some
cma helpers functions to help implementing mmuless display driver
version 2:
- define get_fb_unmapped_area() in drivers/video/fbdev/core/fbmem.c
if HAVE_ARCH_FB_UNMAPPED_AREA is set and get_fb_unmapped_area not
already defined in the architecture
Signed-off-by: Benjamin Gaignard <benjamin.gaignard at linaro.org>
---
drivers/gpu/drm/Kconfig | 4 +--
drivers/gpu/drm/drm_fb_cma_helper.c | 4 +++
drivers/gpu/drm/drm_gem_cma_helper.c | 62 ++++++++++++++++++++++++++++++++++++
drivers/gpu/drm/drm_vm.c | 4 +++
drivers/video/fbdev/core/fbmem.c | 15 +++++++++
include/drm/drm_gem_cma_helper.h | 6 ++++
6 files changed, 93 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 8d9cf73..36c102b 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -6,7 +6,7 @@
#
menuconfig DRM
tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
- depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && MMU && HAS_DMA
+ depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
select HDMI
select FB_CMDLINE
select I2C
@@ -98,7 +98,7 @@ config DRM_LOAD_EDID_FIRMWARE
config DRM_TTM
tristate
- depends on DRM
+ depends on DRM && MMU
help
GPU memory management subsystem for devices with multiple
GPU memory types. Will be enabled automatically if a device driver
diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
index 81b3558..b1414b6 100644
--- a/drivers/gpu/drm/drm_fb_cma_helper.c
+++ b/drivers/gpu/drm/drm_fb_cma_helper.c
@@ -343,8 +343,12 @@ int drm_fb_cma_debugfs_show(struct seq_file *m, void *arg)
static int drm_fb_cma_mmap(struct fb_info *info, struct vm_area_struct *vma)
{
+#ifdef CONFIG_MMU
return dma_mmap_writecombine(info->device, vma, info->screen_base,
info->fix.smem_start, info->fix.smem_len);
+#else
+ return vm_iomap_memory(vma, vma->vm_start, info->fix.smem_len);
+#endif
}
static struct fb_ops drm_fbdev_cma_ops = {
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 1d6c335..de13535 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -318,11 +318,16 @@ static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
vma->vm_flags &= ~VM_PFNMAP;
vma->vm_pgoff = 0;
+#ifdef CONFIG_MMU
ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
cma_obj->paddr, vma->vm_end - vma->vm_start);
if (ret)
drm_gem_vm_close(vma);
+#else
+ ret = vm_iomap_memory(vma, vma->vm_start,
+ (vma->vm_end - vma->vm_start));
+#endif
return ret;
}
@@ -358,6 +363,63 @@ int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
}
EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
+#ifdef CONFIG_MMU
+#define drm_gem_cma_get_unmapped_area NULL
+#else
+unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
+ unsigned long addr,
+ unsigned long len,
+ unsigned long pgoff,
+ unsigned long flags)
+{
+ struct drm_gem_cma_object *cma_obj;
+ struct drm_gem_object *obj = NULL;
+ struct drm_file *priv = filp->private_data;
+ struct drm_device *dev = priv->minor->dev;
+ struct drm_vma_offset_node *node;
+
+ if (drm_device_is_unplugged(dev))
+ return -ENODEV;
+
+ drm_vma_offset_lock_lookup(dev->vma_offset_manager);
+ node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
+ pgoff,
+ len >> PAGE_SHIFT);
+ if (likely(node)) {
+ obj = container_of(node, struct drm_gem_object, vma_node);
+ /*
+ * When the object is being freed, after it hits 0-refcnt it
+ * proceeds to tear down the object. In the process it will
+ * attempt to remove the VMA offset and so acquire this
+ * mgr->vm_lock. Therefore if we find an object with a 0-refcnt
+ * that matches our range, we know it is in the process of being
+ * destroyed and will be freed as soon as we release the lock -
+ * so we have to check for the 0-refcnted object and treat it as
+ * invalid.
+ */
+ if (!kref_get_unless_zero(&obj->refcount))
+ obj = NULL;
+ }
+
+ drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
+
+ if (!obj)
+ return -EINVAL;
+
+ if (!drm_vma_node_is_allowed(node, priv)) {
+ drm_gem_object_unreference_unlocked(obj);
+ return -EACCES;
+ }
+
+ cma_obj = to_drm_gem_cma_obj(obj);
+
+ drm_gem_object_unreference_unlocked(obj);
+
+ return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
+}
+#endif
+EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
+
#ifdef CONFIG_DEBUG_FS
/**
* drm_gem_cma_describe - describe a CMA GEM object for debugfs
diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
index caa4e4c..974e02b 100644
--- a/drivers/gpu/drm/drm_vm.c
+++ b/drivers/gpu/drm/drm_vm.c
@@ -489,6 +489,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
#if defined(__i386__) || defined(__x86_64__)
pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
#else
+#ifdef CONFIG_MMU
/* Ye gads this is ugly. With more thought
we could move this up higher and use
`protection_map' instead. */
@@ -497,6 +498,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
(pte_wrprotect
(__pte(pgprot_val(vma->vm_page_prot)))));
#endif
+#endif
}
vma->vm_ops = &drm_vm_dma_ops;
@@ -573,6 +575,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
#if defined(__i386__) || defined(__x86_64__)
pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
#else
+#ifdef CONFIG_MMU
/* Ye gads this is ugly. With more thought
we could move this up higher and use
`protection_map' instead. */
@@ -581,6 +584,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
(pte_wrprotect
(__pte(pgprot_val(vma->vm_page_prot)))));
#endif
+#endif
}
switch (map->type) {
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 76c1ad9..54488ee 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1492,6 +1492,21 @@ static long fb_compat_ioctl(struct file *file, unsigned int cmd,
return 0;
}
+#if defined(HAVE_ARCH_FB_UNMAPPED_AREA) && !defined(get_fb_unmapped_area)
+unsigned long get_fb_unmapped_area(struct file *filp,
+ unsigned long addr, unsigned long len,
+ unsigned long pgoff, unsigned long flags)
+{
+ struct fb_info * const info = filp->private_data;
+ unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
+
+ if (pgoff > fb_size || len > fb_size - pgoff)
+ return -EINVAL;
+
+ return (unsigned long)info->screen_base + pgoff;
+}
+#endif
+
static const struct file_operations fb_fops = {
.owner = THIS_MODULE,
.read = fb_read,
diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
index acd6af8..177a20d 100644
--- a/include/drm/drm_gem_cma_helper.h
+++ b/include/drm/drm_gem_cma_helper.h
@@ -53,6 +53,12 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
extern const struct vm_operations_struct drm_gem_cma_vm_ops;
+unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
+ unsigned long addr,
+ unsigned long len,
+ unsigned long pgoff,
+ unsigned long flags);
+
#ifdef CONFIG_DEBUG_FS
void drm_gem_cma_describe(struct drm_gem_cma_object *obj, struct seq_file *m);
#endif
--
1.9.1
More information about the dri-devel
mailing list