ACK: [PATCH] drm/fb_cma_helper: Implement fb_mmap callback
Stefan Bader
stefan.bader at canonical.com
Thu Aug 3 13:38:45 UTC 2017
On 03.08.2017 12:17, Paolo Pisati wrote:
> From: Robin Murphy <robin.murphy at arm.com>
>
> BugLink: https://bugs.launchpad.net/bugs/1708417
>
> In the absence of an fb_mmap callback, the fbdev code falls back to a
> naive implementation which relies upon the DMA address being the same
> as the physical address, and the buffer being physically contiguous
> from there. Whilst this often holds for standard CMA allocations via
> the platform's regular DMA ops, if the allocation is provided by an
> IOMMU then such assumptions can fall apart spectacularly.
>
> To resolve this, reroute the fb_mmap call to the appropriate DMA API
> implementation, as per the other cma_helper calls.
>
> Signed-off-by: Robin Murphy <robin.murphy at arm.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> Link: http://patchwork.freedesktop.org/patch/msgid/8fd95ac1440e0f01daad6d4380be3a4c8fa61055.1465301219.git.robin.murphy@arm.com
> (cherry picked from commit ce0c5757681052eb8965209129f28362c3a4d8a7)
> Signed-off-by: Paolo Pisati <paolo.pisati at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---
Limited to specific subtree where it is testable.
> drivers/gpu/drm/drm_fb_cma_helper.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
> index 6349d0c..033f846 100644
> --- a/drivers/gpu/drm/drm_fb_cma_helper.c
> +++ b/drivers/gpu/drm/drm_fb_cma_helper.c
> @@ -23,6 +23,7 @@
> #include <drm/drm_crtc_helper.h>
> #include <drm/drm_gem_cma_helper.h>
> #include <drm/drm_fb_cma_helper.h>
> +#include <linux/dma-mapping.h>
> #include <linux/module.h>
>
> struct drm_fb_cma {
> @@ -220,6 +221,12 @@ int drm_fb_cma_debugfs_show(struct seq_file *m, void *arg)
> EXPORT_SYMBOL_GPL(drm_fb_cma_debugfs_show);
> #endif
>
> +static int drm_fb_cma_mmap(struct fb_info *info, struct vm_area_struct *vma)
> +{
> + return dma_mmap_writecombine(info->device, vma, info->screen_base,
> + info->fix.smem_start, info->fix.smem_len);
> +}
> +
> static struct fb_ops drm_fbdev_cma_ops = {
> .owner = THIS_MODULE,
> .fb_fillrect = drm_fb_helper_sys_fillrect,
> @@ -230,6 +237,7 @@ static struct fb_ops drm_fbdev_cma_ops = {
> .fb_blank = drm_fb_helper_blank,
> .fb_pan_display = drm_fb_helper_pan_display,
> .fb_setcmap = drm_fb_helper_setcmap,
> + .fb_mmap = drm_fb_cma_mmap,
> };
>
> static int drm_fbdev_cma_create(struct drm_fb_helper *helper,
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: OpenPGP digital signature
URL: <https://lists.ubuntu.com/archives/kernel-team/attachments/20170803/4448c9ac/attachment.sig>
More information about the kernel-team
mailing list