On Wed, Nov 30, 2016 at 12:21:24PM +0100, Benjamin Gaignard wrote:
Some platforms without MMU have display drivers where a drm/kms driver could be implemented. Before doing such kind of thing drm/kms must allow to use mmuless devices. This patch proposes to remove MMU configuration flag and add some cma helpers functions to help implementing mmuless display driver
Signed-off-by: Benjamin Gaignard benjamin.gaignard@linaro.org
drivers/gpu/drm/Kconfig | 4 +-- drivers/gpu/drm/drm_fb_cma_helper.c | 20 ++++++++++++ drivers/gpu/drm/drm_gem_cma_helper.c | 62 ++++++++++++++++++++++++++++++++++++
Hacking this into cma helpers feels very wrong to me. mmu-less looks like it works substantially differently enough that it warrants a new set of mmu-less gem helpers. And maybe that will showcase more code-refactoring opportunities between cma helpers, mmu-less helpers and shmem-based gem objects. And if there's none, then I think copypasting is better than ending up in a mess.
drivers/gpu/drm/drm_vm.c | 4 +++ drivers/video/fbdev/core/fbmem.c | 8 +++++ include/drm/drm_gem_cma_helper.h | 6 ++++ 6 files changed, 102 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..a3cef79 100644 --- a/drivers/gpu/drm/drm_fb_cma_helper.c +++ b/drivers/gpu/drm/drm_fb_cma_helper.c @@ -343,10 +343,30 @@ 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 } +#ifdef HAVE_ARCH_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;
+} +EXPORT_SYMBOL_GPL(get_fb_unmapped_area); +#endif
static struct fb_ops drm_fbdev_cma_ops = { .owner = THIS_MODULE, DRM_FB_HELPER_DEFAULT_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) {
drm_vm.c is a legacy horror show. Instead of hacking even more garbage into this, can't we just not compile this for MMU-less platforms? A bunch of stubs in drm_internal.h is all that should be needed for this, since on MMU-less you should never be able to enable one of the legacy drivers which need the exported symbols from this file.
Cheers, Daniel
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 76c1ad9..d6a83bd 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1492,6 +1492,14 @@ static long fb_compat_ioctl(struct file *file, unsigned int cmd, return 0; } +#ifdef HAVE_ARCH_FB_UNMAPPED_AREA +extern unsigned long get_fb_unmapped_area(struct file *filp,
unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags);+#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..79e9dbd 100644 --- a/include/drm/drm_gem_cma_helper.h +++ b/include/drm/drm_gem_cma_helper.h @@ -51,6 +51,12 @@ int drm_gem_cma_dumb_map_offset(struct drm_file *file_priv, struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm, size_t size); +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags);extern const struct vm_operations_struct drm_gem_cma_vm_ops;
#ifdef CONFIG_DEBUG_FS
1.9.1