[PATCH v2 2/5] drm/vkms: map/unmap buffers in [prepare/cleanup]_fb hooks

[Sean Paul]

On Sat, Jul 14, 2018 at 03:20:21PM +0300, Haneen Mohammed wrote:
> This patch map/unmap GEM backing memory to kernel address space
> in prepare/cleanup_fb respectively and cache the virtual address
> for later use.
> 
> Signed-off-by: Haneen Mohammed <hamohammed.sa at gmail.com>
> ---
> Changes in v2:
> - use vkms_gem_vunmap
> 
>  drivers/gpu/drm/vkms/vkms_plane.c | 36 ++++++++++++++++++++++++++++++-
>  1 file changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
> index 9f75b1e2c1c4..877483984897 100644
> --- a/drivers/gpu/drm/vkms/vkms_plane.c
> +++ b/drivers/gpu/drm/vkms/vkms_plane.c
> @@ -7,8 +7,9 @@
>   */
>  
>  #include "vkms_drv.h"
> -#include <drm/drm_plane_helper.h>

nit: This seems unrelated to the patch

>  #include <drm/drm_atomic_helper.h>
> +#include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/drm_plane_helper.h>
>  
>  static const struct drm_plane_funcs vkms_plane_funcs = {
>  	.update_plane		= drm_atomic_helper_update_plane,
> @@ -24,8 +25,41 @@ static void vkms_primary_plane_update(struct drm_plane *plane,
>  {
>  }
>  
> +static int vkms_prepare_fb(struct drm_plane *plane,
> +			   struct drm_plane_state *state)
> +{
> +	struct drm_gem_object *gem_obj;
> +	struct vkms_gem_object *vkms_obj;
> +
> +	if (!state->fb)
> +		return 0;
> +
> +	gem_obj = drm_gem_fb_get_obj(state->fb, 0);
> +	vkms_obj = drm_gem_to_vkms_gem(gem_obj);
> +	vkms_obj->vaddr = vkms_gem_vmap(gem_obj);
> +
> +	if (!vkms_obj->vaddr)

- vkms_gem_vmap() returns ERR_PTR(), not NULL. So IS_ERR_OR_NULL would be
  more appropriate
- You shouldn't be assigning the return of vkms_gem_vmap() to vkms_obj->vaddr
  since vkms_gem_vmap() already does this internally (with proper locks and
  checks)

So you should probably change vkms_gem_vmap() to return int and accept a
vkms_obj upon which it'll populate vaddr for you.

Sean

> +		DRM_ERROR("vmap failed\n");
> +
> +	return drm_gem_fb_prepare_fb(plane, state);
> +}
> +
> +static void vkms_cleanup_fb(struct drm_plane *plane,
> +			    struct drm_plane_state *old_state)
> +{
> +	struct drm_gem_object *gem_obj;
> +
> +	if (!old_state->fb)
> +		return;
> +
> +	gem_obj = drm_gem_fb_get_obj(old_state->fb, 0);
> +	vkms_gem_vunmap(gem_obj);
> +}
> +
>  static const struct drm_plane_helper_funcs vkms_primary_helper_funcs = {
>  	.atomic_update		= vkms_primary_plane_update,
> +	.prepare_fb		= vkms_prepare_fb,
> +	.cleanup_fb		= vkms_cleanup_fb,
>  };
>  
>  struct drm_plane *vkms_plane_init(struct vkms_device *vkmsdev)
> -- 
> 2.17.1
> 

-- 
Sean Paul, Software Engineer, Google / Chromium OS