[Intel-gfx] [PATCH RFC v2 3/3] drm/i915/display: Implement fb_mmap callback function

[Nirmoy Das]

If stolen memory allocation fails for fbdev, the driver will
fallback to system memory. Calculation of smem_start is wrong
for such framebuffer objs if the platform comes with no gmadr or
no aperture. Solve this by adding fb_mmap callback which also gives
driver more control.

v2: Remove unused var.

Signed-off-by: Nirmoy Das <nirmoy....@intel.com>
---
 drivers/gpu/drm/i915/display/intel_fbdev.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c 
b/drivers/gpu/drm/i915/display/intel_fbdev.c
index 98ae3a3a986a..161c2610976a 100644
--- a/drivers/gpu/drm/i915/display/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
@@ -40,8 +40,10 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_fourcc.h>
+#include <drm/drm_gem_framebuffer_helper.h>
 
 #include "gem/i915_gem_lmem.h"
+#include "gem/i915_gem_mman.h"
 
 #include "i915_drv.h"
 #include "intel_display_types.h"
@@ -120,6 +122,22 @@ static int intel_fbdev_pan_display(struct 
fb_var_screeninfo *var,
        return ret;
 }
 
+#define to_intel_fbdev(x) container_of(x, struct intel_fbdev, helper)
+static int intel_fbdev_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+       struct intel_fbdev *fbdev = to_intel_fbdev(info->par);
+       struct drm_gem_object *bo = drm_gem_fb_get_obj(&fbdev->fb->base, 0);
+       struct drm_i915_gem_object *obj = to_intel_bo(bo);
+
+       vma->vm_page_prot =
+                       pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+
+       if (obj->stolen)
+               return vm_iomap_memory(vma, info->fix.smem_start,
+                                      info->fix.smem_len);
+
+       return i915_gem_object_mmap(obj, vma);
+}
 static const struct fb_ops intelfb_ops = {
        .owner = THIS_MODULE,
        DRM_FB_HELPER_DEFAULT_OPS,
@@ -131,6 +149,7 @@ static const struct fb_ops intelfb_ops = {
        .fb_imageblit = drm_fb_helper_cfb_imageblit,
        .fb_pan_display = intel_fbdev_pan_display,
        .fb_blank = intel_fbdev_blank,
+       .fb_mmap = intel_fbdev_mmap,
 };
 
 static int intelfb_alloc(struct drm_fb_helper *helper,
-- 
2.39.0