Add infrastructure needed for CRC support

This patch add the necessary functions to map GEM backing memory into the kernel's virtual address space.

Signed-off-by Haneen Mohammed <[email protected]>

---
 drivers/gpu/drm/vkms/vkms_drv.c |  2 ++
 drivers/gpu/drm/vkms/vkms_drv.h |  5 ++++
 drivers/gpu/drm/vkms/vkms_gem.c | 50 +++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+)

drivers/gpu/drm/vkms/vkms_drv.c +0 -0

index fe93f8c17997..e48c8eeb495a 100644

drivers/gpu/drm/vkms/vkms_drv.c +0 -0

 	.name			= DRIVER_NAME,
 	.desc			= DRIVER_DESC,

drivers/gpu/drm/vkms/vkms_drv.h +5 -0

index 76f1720f81a5..d339a8108d85 100644
@@ -35,6 +35,7 @@ struct vkms_gem_object {
 	struct drm_gem_object gem;
 	struct mutex pages_lock; /* Page lock used in page fault handler */
 	struct page **pages;
+	void *vaddr;
 };
 
 int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,

@@ -58,4 +59,8 @@ int vkms_dumb_create(struct drm_file *file, struct drm_device *dev,
 int vkms_dumb_map(struct drm_file *file, struct drm_device *dev,
 		  u32 handle, u64 *offset);
 
+void vkms_gem_free_object(struct drm_gem_object *obj);
+
+void *vkms_gem_vmap(struct drm_gem_object *obj);
+
 #endif /* _VKMS_DRV_H_ */

drivers/gpu/drm/vkms/vkms_gem.c +0 -0

index 9f820f56b9e0..249855dded63 100644

drivers/gpu/drm/vkms/vkms_gem.c +43 -0

+	mutex_destroy(&vkms_obj->pages_lock);
+	drm_gem_object_release(obj);
+	kfree(vkms_obj);
+}
+
+struct page **get_pages(struct vkms_gem_object *vkms_obj)
+{
+	struct drm_gem_object *gem_obj = &vkms_obj->gem;
+	struct page **pages = vkms_obj->pages;
+
+	if (!pages) {
+		mutex_lock(&vkms_obj->pages_lock);
+		pages = drm_gem_get_pages(gem_obj);
+		if (IS_ERR(pages)) {
+			mutex_unlock(&vkms_obj->pages_lock);
+			return pages;
+		}
+
+		vkms_obj->pages = pages;
+		mutex_unlock(&vkms_obj->pages_lock);
+	}
+
+	return pages;
+}
+
+void *vkms_gem_vmap(struct drm_gem_object *obj)
+{
+	void *vaddr = NULL;
+	struct vkms_gem_object *vkms_obj = container_of(obj,
+							struct vkms_gem_object,
+							gem);
+	unsigned int n_pages = obj->size >> PAGE_SHIFT;
+	struct page **pages = get_pages(vkms_obj);
+
+	if (IS_ERR(pages)) {
+		DRM_INFO("pages allocation failed %ld\n", PTR_ERR(pages));
+		return vaddr;
+	}
+
+	vaddr = vmap(pages, n_pages, VM_MAP, PAGE_KERNEL);
+
+	return vaddr;
+}

Signature · 1 line

2.17.1

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 <[email protected]>

---
 drivers/gpu/drm/vkms/vkms_plane.c | 41 +++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

drivers/gpu/drm/vkms/vkms_plane.c +24 -0

index f7f63143f6d0..f464eb0e05dd 100644
@@ -9,6 +9,7 @@
 #include "vkms_drv.h"
 #include <drm/drm_plane_helper.h>
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
 
 static const struct drm_plane_funcs vkms_plane_funcs = {
 	.update_plane		= drm_atomic_helper_update_plane,

@@ -30,9 +31,49 @@ 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 = container_of(gem_obj, struct vkms_gem_object, gem);
+	vkms_obj->vaddr = vkms_gem_vmap(gem_obj);
+
+	if (!vkms_obj->vaddr)
+		DRM_INFO("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;

drivers/gpu/drm/vkms/vkms_plane.c +5 -0

+	}
+}
+
 static const struct drm_plane_helper_funcs vkms_primary_helper_funcs = {
 	.atomic_check		= vkms_plane_atomic_check,
 	.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)

Signature · 1 line

2.17.1

Call atomic_helper_check_plane_state to clip plane coordinates.

Signed-off-by Haneen Mohammed <[email protected]>

---
 drivers/gpu/drm/vkms/vkms_plane.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

drivers/gpu/drm/vkms/vkms_plane.c +6 -2

index f464eb0e05dd..bf37aebac0fb 100644
@@ -7,9 +7,10 @@
  */
 
 #include "vkms_drv.h"
-#include <drm/drm_plane_helper.h>
+#include <drm/drm_atomic.h>
 #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,

@@ -23,7 +24,20 @@ static const struct drm_plane_funcs vkms_plane_funcs = {
 static int vkms_plane_atomic_check(struct drm_plane *plane,
 				   struct drm_plane_state *state)
 {
-	return 0;
+	struct drm_crtc_state *crtc_state;
+
+	if (!state->fb || !state->crtc)
+		return 0;

drivers/gpu/drm/vkms/vkms_plane.c +0 -0

 }
 
 static void vkms_primary_plane_update(struct drm_plane *plane,

Signature · 1 line

2.17.1

Subclass CRTC state struct to enable storing driver's private state. This patch only adds the base drm_crtc_state struct and the atomic functions that handle it.

Signed-off-by Haneen Mohammed <[email protected]>

---
 drivers/gpu/drm/vkms/vkms_crtc.c | 55 ++++++++++++++++++++++++++++++--
 drivers/gpu/drm/vkms/vkms_drv.h  |  8 +++++
 2 files changed, 60 insertions(+), 3 deletions(-)

drivers/gpu/drm/vkms/vkms_crtc.c +3 -0

index 84cc05506b09..56206437647d 100644
@@ -10,13 +10,62 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc_helper.h>
 
+static void vkms_crtc_reset(struct drm_crtc *crtc)
+{
+	struct vkms_crtc_state *state = NULL;

drivers/gpu/drm/vkms/vkms_crtc.c +39 -3

+	if (!state)
+		return;
+
+	crtc->state = &state->base;
+	crtc->state->crtc = crtc;
+}
+
+static struct drm_crtc_state *
+vkms_crtc_duplicate_state(struct drm_crtc *crtc)
+{
+	struct vkms_crtc_state *state;
+
+	if (WARN_ON(!crtc->state))
+		return NULL;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return NULL;
+
+	__drm_atomic_helper_crtc_duplicate_state(crtc, &state->base);
+
+	return &state->base;
+}
+
+static void vkms_crtc_destroy_state(struct drm_crtc *crtc,
+				    struct drm_crtc_state *state)
+{
+	struct vkms_crtc_state *vkms_state;
+
+	vkms_state = container_of(state, struct vkms_crtc_state, base);
+
+	__drm_atomic_helper_crtc_destroy_state(state);
+	kfree(vkms_state);
+}
+
 static const struct drm_crtc_funcs vkms_crtc_funcs = {
 	.set_config             = drm_atomic_helper_set_config,
 	.destroy                = drm_crtc_cleanup,
 	.page_flip              = drm_atomic_helper_page_flip,
-	.reset                  = drm_atomic_helper_crtc_reset,
-	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
-	.atomic_destroy_state   = drm_atomic_helper_crtc_destroy_state,
+
+	.reset                  = vkms_crtc_reset,
+	.atomic_duplicate_state = vkms_crtc_duplicate_state,
+	.atomic_destroy_state   = vkms_crtc_destroy_state,
 };
 
 static int vkms_crtc_atomic_check(struct drm_crtc *crtc,

drivers/gpu/drm/vkms/vkms_drv.h +8 -0

index d339a8108d85..61e367d32308 100644
@@ -19,6 +19,14 @@ static const u32 vkms_formats[] = {
 	DRM_FORMAT_XRGB8888,
 };
 
+/**
+ * vkms_crtc_state - Driver specific CRTC state
+ * @base: base CRTC state
+ */
+struct vkms_crtc_state {
+	struct drm_crtc_state base;
+};
+
 struct vkms_output {
 	struct drm_crtc crtc;
 	struct drm_encoder encoder;

Signature · 1 line

2.17.1

drivers/gpu/drm/vkms/vkms_gem.c +5 -0

+struct page **get_pages(struct vkms_gem_object *vkms_obj)
+{
+       struct drm_gem_object *gem_obj = &vkms_obj->gem;
+       struct page **pages = vkms_obj->pages;
+

Quoting Haneen Mohammed (2018-07-09 16:44:26)

Quoted 5 lines

drivers/gpu/drm/vkms/vkms_gem.c +5 -0

+struct page **get_pages(struct vkms_gem_object *vkms_obj)
+{
+       struct drm_gem_object *gem_obj = &vkms_obj->gem;
+       struct page **pages = vkms_obj->pages;
+

drivers/gpu/drm/vkms/vkms_gem.c int vkms_dumb_map(struct drm_file *file, struct drm_device *dev, · line 195

Quoted 10 lines

drivers/gpu/drm/vkms/vkms_gem.c +10 -0

+       if (!pages) {
+               mutex_lock(&vkms_obj->pages_lock);
+               pages = drm_gem_get_pages(gem_obj);
+               if (IS_ERR(pages)) {
+                       mutex_unlock(&vkms_obj->pages_lock);
+                       return pages;
+               }
+
+               vkms_obj->pages = pages;
+               mutex_unlock(&vkms_obj->pages_lock);

You have a race here with two callers setting pages. Trivially you fix it by checking if (!pages) again inside the lock, but the lock is superfluous in this case:

	if (!vkms_obj->pages) {
		srtuct pages **pages;

		pages = drm_gem_get_pages(gem_obj);
		if (IS_ERR(pages))
			return pages;
		
		if (cmpxchg(&vkms_obj->pages, NULL, pages))
			put_pages(pages);

		/* barrier() is implied */
	}

	return vkms_obj->pages;

-Chris

Quoted 5 lines · Haneen Mohammed

Subclass CRTC state struct to enable storing driver's private state. This patch only adds the base drm_crtc_state struct and the atomic functions that handle it.

Signed-off-by Haneen Mohammed <[email protected]>

Reviewed-by Daniel Vetter <[email protected]>

Quoted 22 lines

---
 drivers/gpu/drm/vkms/vkms_crtc.c | 55 ++++++++++++++++++++++++++++++--
 drivers/gpu/drm/vkms/vkms_drv.h  |  8 +++++
 2 files changed, 60 insertions(+), 3 deletions(-)

drivers/gpu/drm/vkms/vkms_crtc.c +9 -0

index 84cc05506b09..56206437647d 100644
@@ -10,13 +10,62 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc_helper.h>
 
+static void vkms_crtc_reset(struct drm_crtc *crtc)
+{
+	struct vkms_crtc_state *state = NULL;
+
+	if (crtc->state) {
+		state = container_of(crtc->state, struct vkms_crtc_state,
+				     base);
+		__drm_atomic_helper_crtc_destroy_state(crtc->state);
+		kfree(state);

drivers/gpu/drm/vkms/vkms_crtc.c line 25

Quoted 4 lines

drivers/gpu/drm/vkms/vkms_crtc.c +4 -0

+		crtc->state = NULL;
+	}
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);

Hm, using kzalloc here is a good idea instead of kmalloc like in the default functions. Care to write a patch for drm_atomic_helper to replace all the kmalloc with kzalloc?

Thanks, Daniel

Quoted 57 lines

drivers/gpu/drm/vkms/vkms_crtc.c +39 -3

+	if (!state)
+		return;
+
+	crtc->state = &state->base;
+	crtc->state->crtc = crtc;
+}
+
+static struct drm_crtc_state *
+vkms_crtc_duplicate_state(struct drm_crtc *crtc)
+{
+	struct vkms_crtc_state *state;
+
+	if (WARN_ON(!crtc->state))
+		return NULL;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return NULL;
+
+	__drm_atomic_helper_crtc_duplicate_state(crtc, &state->base);
+
+	return &state->base;
+}
+
+static void vkms_crtc_destroy_state(struct drm_crtc *crtc,
+				    struct drm_crtc_state *state)
+{
+	struct vkms_crtc_state *vkms_state;
+
+	vkms_state = container_of(state, struct vkms_crtc_state, base);
+
+	__drm_atomic_helper_crtc_destroy_state(state);
+	kfree(vkms_state);
+}
+
 static const struct drm_crtc_funcs vkms_crtc_funcs = {
 	.set_config             = drm_atomic_helper_set_config,
 	.destroy                = drm_crtc_cleanup,
 	.page_flip              = drm_atomic_helper_page_flip,
-	.reset                  = drm_atomic_helper_crtc_reset,
-	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
-	.atomic_destroy_state   = drm_atomic_helper_crtc_destroy_state,
+
+	.reset                  = vkms_crtc_reset,
+	.atomic_duplicate_state = vkms_crtc_duplicate_state,
+	.atomic_destroy_state   = vkms_crtc_destroy_state,
 };
 
 static int vkms_crtc_atomic_check(struct drm_crtc *crtc,

drivers/gpu/drm/vkms/vkms_drv.h +0 -0

index d339a8108d85..61e367d32308 100644
@@ -19,6 +19,14 @@ static const u32 vkms_formats[] = {
 	DRM_FORMAT_XRGB8888,
 };
 

Quoted 14 lines

drivers/gpu/drm/vkms/vkms_drv.h +8 -0

+/**
+ * vkms_crtc_state - Driver specific CRTC state
+ * @base: base CRTC state
+ */
+struct vkms_crtc_state {
+	struct drm_crtc_state base;
+};
+
 struct vkms_output {
 	struct drm_crtc crtc;
 	struct drm_encoder encoder;

Signature · 1 line

2.17.1

Signature · 3 lines

Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch