On Thu, Dec 01, 2016 at 08:21:11AM +0100, Benjamin Gaignard wrote:
2016-12-01 7:56 GMT+01:00 Daniel Vetter daniel@ffwll.ch:
On Wed, Nov 30, 2016 at 02:19:18PM +0100, Benjamin Gaignard wrote:
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@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 driverdiff --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
Ok, me asking for a separate helper was probably too much. The #ifdefs here are still ugly, but on 2nd thought this just looks like the dma api is broken on no-mmu? Shouldn't we instead have a patch somewhere which gives us a working dma_mmap_wc on nommu platforms?
I not sure that dma_mmap_wc is broken for all nommu platforms, but at least for ARM nommu it return an error: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/ar...
Could it be an alternative to call vm_iomap_memory if dma_map_wc has failed and !CONFIG_MMU ?
Sprinkle #ifdefs all over the place is imo the problem, not what exactly it looks like. Imo this should be fixed in dma-mapping.c.
And if core maintainers hate that, then we need to define a dma_mmap_wc in drm headers which works better than the core one ;-) Something like:
#ifdef NOMMU #define dma_mmap_wc drm_dma_mmap_wc
static inline drm_dma_mmap_wc( .... ) { vm_remap_memory( ....); } #endif
We should probably create a drm-core.h to collect all these (we have a metric pile of them in i915 for various things that are too hard to get merged for no good reason).
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
Depending upon how it's used it might be better to stub it out ...
This function shouldn't be called in MMU case but I can remove the flag and compile it for any case
+#else +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags)With no user and no kerneldoc I kinda have no idea what this is even for. The name also doesn't help, it says "get_unmapped_area", but very clearly you're returning a kernel vaddr cast to a long (and with ERR_PTR semantics on top, but non-standard). Why is this not called get_vaddr?
This function will be used in driver file_operations structure to set get_unmapped_area field. For example v4l2 driver use it: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers... I don't have found so much examples of that but each time they have keep "get_unmapped_area" in function name so I just do the same.
In Documentation/nommu-mmap.txt you have few words about get_unmapped_area()
Hm ok. I think it's time to digg out an old idea I've had:
#define DRM_GEM_CMA_FOPS(driver) \ static const struct file_operations driver ## _drm_fops = { \ .owner = THIS_MODULE, \ .open = drm_open, \ .release = drm_release, \ .unlocked_ioctl = drm_ioctl, \ .compat_ioctl = drm_compat_ioctl, \ .poll = drm_poll, \ .read = drm_read, \ .llseek = no_llseek, \ .mmap = drm_gem_cma_mmap, \ }; \
Then you have one nice place to put the NOMMU #ifdeffery. Would be great to roll this out to drivers.
Still need kerneldoc for this new hook, with a reference to Documentation/nommu-mmap.txt.
I think with that bit of polish&abstraction it makes sense to keep this all in cma helpers itself. -Daniel
-Daniel
+{
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
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
-- Benjamin Gaignard
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