[PATCHv4,1/3] drm/vgem: Add a dummy platform device

Commit Message

Laura Abbott May 4, 2017, 6:45 p.m. UTC

The vgem driver is currently registered independent of any actual
device. Some usage of the dmabuf APIs require an actual device structure
to do anything. Register a dummy platform device for use with dmabuf.

Reviewed-by: Chris Wilson <[e-mail]>
Signed-off-by: Laura Abbott <[e-mail]>
---
v4: Switch from the now removed platformdev to a static platform device.
---
 drivers/gpu/drm/vgem/vgem_drv.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

Comments

Chris Wilson May 4, 2017, 8:23 p.m. UTC | #1

On Thu, May 04, 2017 at 11:45:46AM -0700, Laura Abbott wrote:
> 
> The vgem driver is currently registered independent of any actual
> device. Some usage of the dmabuf APIs require an actual device structure
> to do anything. Register a dummy platform device for use with dmabuf.
> 
> Reviewed-by: Chris Wilson <[e-mail]>
> Signed-off-by: Laura Abbott <[e-mail]>
> ---
> v4: Switch from the now removed platformdev to a static platform device.

I was thinking of avoiding the static, i.e.

static struct vgem_device {
	struct drm_device drm;

	struct device *platform;
} *vgem_device;

vgem_init():

vgem_device = kzalloc(sizeof(*vgem_device), GFP_KERNEEL);

ret = drm_dev_init(&vgem_device->drm, &vgem_drv, NULL);

vgem_device->platform = platform_device_register_simple("vgem");

And then platform_device_unregister() should be done in a new
vgem_drv.release callback.

I'm not going to insist upon it as I can send a patch to move over to
the "modern" drm_device subclassing later.
-Chris

Patch

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 9fee38a..d1d98af 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -42,6 +42,8 @@ 
 #define DRIVER_MAJOR	1
 #define DRIVER_MINOR	0
 
+static struct platform_device *vgem_platform;
+
 static void vgem_gem_free_object(struct drm_gem_object *obj)
 {
 	struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
@@ -335,11 +337,20 @@  static int __init vgem_init(void)
 	int ret;
 
 	vgem_device = drm_dev_alloc(&vgem_driver, NULL);
-	if (IS_ERR(vgem_device)) {
-		ret = PTR_ERR(vgem_device);
+	if (IS_ERR(vgem_device))
+		return PTR_ERR(vgem_device);
+
+	vgem_platform = platform_device_register_simple("vgem",
+					-1, NULL, 0);
+
+	if (!vgem_platform) {
+		ret = -ENODEV;
 		goto out;
 	}
 
+	dma_coerce_mask_and_coherent(&vgem_platform->dev,
+					DMA_BIT_MASK(64));
+
 	ret  = drm_dev_register(vgem_device, 0);
 	if (ret)
 		goto out_unref;
@@ -347,13 +358,15 @@  static int __init vgem_init(void)
 	return 0;
 
 out_unref:
-	drm_dev_unref(vgem_device);
+	platform_device_unregister(vgem_platform);
 out:
+	drm_dev_unref(vgem_device);
 	return ret;
 }
 
 static void __exit vgem_exit(void)
 {
+	platform_device_unregister(vgem_platform);
 	drm_dev_unregister(vgem_device);
 	drm_dev_unref(vgem_device);
 }