* [RFC v2 1/1] drm: allow to use mmuless SoC
@ 2016-11-30 13:19 Benjamin Gaignard
2016-11-30 13:27 ` Laurent Pinchart
2016-12-01 6:56 ` Daniel Vetter
0 siblings, 2 replies; 6+ messages in thread
From: Benjamin Gaignard @ 2016-11-30 13:19 UTC (permalink / raw)
To: dri-devel, airlied, daniel, robdclark, laurent.pinchart
Cc: yannick.fertre, linaro-kernel, philippe.cornu
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 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
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^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [RFC v2 1/1] drm: allow to use mmuless SoC
2016-11-30 13:19 [RFC v2 1/1] drm: allow to use mmuless SoC Benjamin Gaignard
@ 2016-11-30 13:27 ` Laurent Pinchart
2016-12-01 6:56 ` Daniel Vetter
1 sibling, 0 replies; 6+ messages in thread
From: Laurent Pinchart @ 2016-11-30 13:27 UTC (permalink / raw)
To: Benjamin Gaignard
Cc: linaro-kernel, philippe.cornu, dri-devel, yannick.fertre, airlied
Hi Benjamin,
Thank you for the patch.
On Wednesday 30 Nov 2016 14:19:18 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(-)
[snip]
> 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)
Only blackfin and sparc define HAVE_ARCH_FB_UNMAPPED_AREA, and both of them
provide an implementation of 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,
[snip]
--
Regards,
Laurent Pinchart
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [RFC v2 1/1] drm: allow to use mmuless SoC
2016-11-30 13:19 [RFC v2 1/1] drm: allow to use mmuless SoC Benjamin Gaignard
2016-11-30 13:27 ` Laurent Pinchart
@ 2016-12-01 6:56 ` Daniel Vetter
2016-12-01 7:03 ` Benjamin Gaignard
2016-12-01 7:21 ` Benjamin Gaignard
1 sibling, 2 replies; 6+ messages in thread
From: Daniel Vetter @ 2016-12-01 6:56 UTC (permalink / raw)
To: Benjamin Gaignard
Cc: linaro-kernel, philippe.cornu, dri-devel, yannick.fertre,
laurent.pinchart, airlied
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 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
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?
> 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 ...
> +#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?
-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
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* Re: [RFC v2 1/1] drm: allow to use mmuless SoC
2016-12-01 6:56 ` Daniel Vetter
@ 2016-12-01 7:03 ` Benjamin Gaignard
2016-12-01 7:21 ` Benjamin Gaignard
1 sibling, 0 replies; 6+ messages in thread
From: Benjamin Gaignard @ 2016-12-01 7:03 UTC (permalink / raw)
To: Daniel Vetter
Cc: Linaro Kernel Mailman List, Philippe Cornu,
dri-devel@lists.freedesktop.org, Yannick Fertre, Laurent Pinchart,
Dave Airlie
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 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
>
> 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?
>
>> 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 ...
>
>> +#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?
> -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
Graphic Study Group
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [RFC v2 1/1] drm: allow to use mmuless SoC
2016-12-01 6:56 ` Daniel Vetter
2016-12-01 7:03 ` Benjamin Gaignard
@ 2016-12-01 7:21 ` Benjamin Gaignard
2016-12-01 8:21 ` Daniel Vetter
1 sibling, 1 reply; 6+ messages in thread
From: Benjamin Gaignard @ 2016-12-01 7:21 UTC (permalink / raw)
To: Daniel Vetter
Cc: Linaro Kernel Mailman List, Philippe Cornu,
dri-devel@lists.freedesktop.org, Yannick Fertre, Laurent Pinchart,
Dave Airlie
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 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
>
> 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/arm/mm/dma-mapping.c#n851
Could it be an alternative to call vm_iomap_memory if dma_map_wc has
failed and !CONFIG_MMU ?
>> 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/media/v4l2-core/v4l2-dev.c#n462
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()
> -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
Graphic Study Group
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
_______________________________________________
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* Re: [RFC v2 1/1] drm: allow to use mmuless SoC
2016-12-01 7:21 ` Benjamin Gaignard
@ 2016-12-01 8:21 ` Daniel Vetter
0 siblings, 0 replies; 6+ messages in thread
From: Daniel Vetter @ 2016-12-01 8:21 UTC (permalink / raw)
To: Benjamin Gaignard
Cc: Linaro Kernel Mailman List, Philippe Cornu,
dri-devel@lists.freedesktop.org, Yannick Fertre, Laurent Pinchart,
Dave Airlie
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 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
> >
> > 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/arm/mm/dma-mapping.c#n851
>
> 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/media/v4l2-core/v4l2-dev.c#n462
> 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
>
> Graphic Study Group
>
> Linaro.org │ Open source software for ARM SoCs
>
> Follow Linaro: Facebook | Twitter | Blog
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-12-01 8:21 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-11-30 13:19 [RFC v2 1/1] drm: allow to use mmuless SoC Benjamin Gaignard
2016-11-30 13:27 ` Laurent Pinchart
2016-12-01 6:56 ` Daniel Vetter
2016-12-01 7:03 ` Benjamin Gaignard
2016-12-01 7:21 ` Benjamin Gaignard
2016-12-01 8:21 ` Daniel Vetter
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