Add support for damage handling and deferred I/O to fbdev-dma. This
enables fbdev-dma to support all DMA-memory-based DRM drivers, even
such with a dirty callback in their framebuffers.

The patch adds the code for deferred I/O and also sets a dedicated
helper for struct fb_ops.fb_mmap that support coherent mappings.

v3:
- init fb_ops with FB_GEN_DEFAULT_DEFERRED_DMAMEM_OPS() (Javier)

Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
Reviewed-by: Javier Martinez Canillas <javi...@redhat.com>
---
 drivers/gpu/drm/drm_fbdev_dma.c | 65 ++++++++++++++++++++++++++-------
 1 file changed, 51 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/drm_fbdev_dma.c b/drivers/gpu/drm/drm_fbdev_dma.c
index 6c9427bb4053b..5eeb5164e9e2b 100644
--- a/drivers/gpu/drm/drm_fbdev_dma.c
+++ b/drivers/gpu/drm/drm_fbdev_dma.c
@@ -4,6 +4,7 @@
 
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_fb_dma_helper.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_gem_dma_helper.h>
@@ -35,6 +36,22 @@ static int drm_fbdev_dma_fb_release(struct fb_info *info, 
int user)
        return 0;
 }
 
+FB_GEN_DEFAULT_DEFERRED_DMAMEM_OPS(drm_fbdev_dma,
+                                  drm_fb_helper_damage_range,
+                                  drm_fb_helper_damage_area);
+
+static int drm_fbdev_dma_fb_mmap(struct fb_info *info, struct vm_area_struct 
*vma)
+{
+       struct drm_fb_helper *fb_helper = info->par;
+       struct drm_framebuffer *fb = fb_helper->fb;
+       struct drm_gem_dma_object *dma = drm_fb_dma_get_gem_obj(fb, 0);
+
+       if (!dma->map_noncoherent)
+               vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
+
+       return fb_deferred_io_mmap(info, vma);
+}
+
 static void drm_fbdev_dma_fb_destroy(struct fb_info *info)
 {
        struct drm_fb_helper *fb_helper = info->par;
@@ -51,20 +68,13 @@ static void drm_fbdev_dma_fb_destroy(struct fb_info *info)
        kfree(fb_helper);
 }
 
-static int drm_fbdev_dma_fb_mmap(struct fb_info *info, struct vm_area_struct 
*vma)
-{
-       struct drm_fb_helper *fb_helper = info->par;
-
-       return drm_gem_prime_mmap(fb_helper->buffer->gem, vma);
-}
-
 static const struct fb_ops drm_fbdev_dma_fb_ops = {
        .owner = THIS_MODULE,
        .fb_open = drm_fbdev_dma_fb_open,
        .fb_release = drm_fbdev_dma_fb_release,
-       __FB_DEFAULT_DMAMEM_OPS_RDWR,
+       __FB_DEFAULT_DEFERRED_OPS_RDWR(drm_fbdev_dma),
        DRM_FB_HELPER_DEFAULT_OPS,
-       __FB_DEFAULT_DMAMEM_OPS_DRAW,
+       __FB_DEFAULT_DEFERRED_OPS_DRAW(drm_fbdev_dma),
        .fb_mmap = drm_fbdev_dma_fb_mmap,
        .fb_destroy = drm_fbdev_dma_fb_destroy,
 };
@@ -98,10 +108,6 @@ static int drm_fbdev_dma_helper_fb_probe(struct 
drm_fb_helper *fb_helper,
        dma_obj = to_drm_gem_dma_obj(buffer->gem);
 
        fb = buffer->fb;
-       if (drm_WARN_ON(dev, fb->funcs->dirty)) {
-               ret = -ENODEV; /* damage handling not supported; use generic 
emulation */
-               goto err_drm_client_buffer_delete;
-       }
 
        ret = drm_client_buffer_vmap(buffer, &map);
        if (ret) {
@@ -112,7 +118,7 @@ static int drm_fbdev_dma_helper_fb_probe(struct 
drm_fb_helper *fb_helper,
        }
 
        fb_helper->buffer = buffer;
-       fb_helper->fb = buffer->fb;
+       fb_helper->fb = fb;
 
        info = drm_fb_helper_alloc_info(fb_helper);
        if (IS_ERR(info)) {
@@ -133,8 +139,19 @@ static int drm_fbdev_dma_helper_fb_probe(struct 
drm_fb_helper *fb_helper,
        info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
        info->fix.smem_len = info->screen_size;
 
+       /* deferred I/O */
+       fb_helper->fbdefio.delay = HZ / 20;
+       fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
+
+       info->fbdefio = &fb_helper->fbdefio;
+       ret = fb_deferred_io_init(info);
+       if (ret)
+               goto err_drm_fb_helper_release_info;
+
        return 0;
 
+err_drm_fb_helper_release_info:
+       drm_fb_helper_release_info(fb_helper);
 err_drm_client_buffer_vunmap:
        fb_helper->fb = NULL;
        fb_helper->buffer = NULL;
@@ -144,8 +161,28 @@ static int drm_fbdev_dma_helper_fb_probe(struct 
drm_fb_helper *fb_helper,
        return ret;
 }
 
+static int drm_fbdev_dma_helper_fb_dirty(struct drm_fb_helper *helper,
+                                        struct drm_clip_rect *clip)
+{
+       struct drm_device *dev = helper->dev;
+       int ret;
+
+       /* Call damage handlers only if necessary */
+       if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
+               return 0;
+
+       if (helper->fb->funcs->dirty) {
+               ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
+               if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", 
ret))
+                       return ret;
+       }
+
+       return 0;
+}
+
 static const struct drm_fb_helper_funcs drm_fbdev_dma_helper_funcs = {
        .fb_probe = drm_fbdev_dma_helper_fb_probe,
+       .fb_dirty = drm_fbdev_dma_helper_fb_dirty,
 };
 
 /*
-- 
2.44.0

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