Hi Benjamin,
Thank you for the patch.
On Wednesday 30 Nov 2016 12:21:24 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@xxxxxxxxxx>
> ---
> drivers/gpu/drm/Kconfig | 4 +--
> drivers/gpu/drm/drm_fb_cma_helper.c | 20 ++++++++++++
> drivers/gpu/drm/drm_gem_cma_helper.c | 62 +++++++++++++++++++++++++++++++++
> drivers/gpu/drm/drm_vm.c | 4 +++
I'll let someone more knowledgeable than me comment on these two files.
> drivers/video/fbdev/core/fbmem.c | 8 +++++
> include/drm/drm_gem_cma_helper.h | 6 ++++
> 6 files changed, 102 insertions(+), 2 deletions(-)
[snip]
> 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
Shouldn't this be #ifndef ? When the symbol is defined the implementation is
provided by the architecture.
By the way, given that you provide a generic implementation here, what's the
reason some architecture need to implement the function in a special way ?
Couldn't we come up with a generic implementation across all architectures ?
> +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);
Shouldn't this be defined somewhere in drivers/video/ instead, as the code is
fbdev-specific and only used in drivers/video/fbdev/core/fbmem.c ?
> +#endif
> +
> static struct fb_ops drm_fbdev_cma_ops = {
> .owner = THIS_MODULE,
> DRM_FB_HELPER_DEFAULT_OPS,
[snip]
> 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
This should come from a header file.
> 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
--
Regards,
Laurent Pinchart
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