[PATCH v3 5/7] drm/gem: Store client buffer mappings as struct dma_buf_map

Thomas Zimmermann
2020-09-29T15:16:56Z

Kernel DRM clients now store their framebuffer address in an instance
of struct dma_buf_map. Depending on the buffer's location, the address
refers to system or I/O memory.

Callers of drm_client_buffer_vmap() receive a copy of the value in
the call's supplied arguments. It can be accessed and modified with
dma_buf_map interfaces.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
drivers/gpu/drm/drm_client.c | 34 +++++++++++++++++++--------------
drivers/gpu/drm/drm_fb_helper.c | 23 +++++++++++++---------
include/drm/drm_client.h | 7 ++++---
3 files changed, 38 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index ac0082bed966..fe573acf1067 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -235,7 +235,7 @@ static void drm_client_buffer_delete(struct drm_client_buffer *buffer)
{
struct drm_device *dev = buffer->client->dev;

- drm_gem_vunmap(buffer->gem, buffer->vaddr);
+ drm_gem_vunmap(buffer->gem, &buffer->map);

if (buffer->gem)
drm_gem_object_put(buffer->gem);
@@ -291,25 +291,31 @@ drm_client_buffer_create(struct drm_client_dev *client, u32 width, u32 height, u
/**
* drm_client_buffer_vmap - Map DRM client buffer into address space
* @buffer: DRM client buffer
+ * @map_copy: Returns the mapped memory's address
*
* This function maps a client buffer into kernel address space. If the
- * buffer is already mapped, it returns the mapping's address.
+ * buffer is already mapped, it returns the existing mapping's address.
*
* Client buffer mappings are not ref'counted. Each call to
* drm_client_buffer_vmap() should be followed by a call to
* drm_client_buffer_vunmap(); or the client buffer should be mapped
* throughout its lifetime.
*
+ * The returned address is a copy of the internal value. In contrast to
+ * other vmap interfaces, you don't need it for the client's vunmap
+ * function. So you can modify it at will during blit and draw operations.
+ *
* Returns:
- * The mapped memory's address
+ * 0 on success, or a negative errno code otherwise.
*/
-void *drm_client_buffer_vmap(struct drm_client_buffer *buffer)
+int
+drm_client_buffer_vmap(struct drm_client_buffer *buffer, struct dma_buf_map *map_copy)
{
- struct dma_buf_map map;
+ struct dma_buf_map *map = &buffer->map;
int ret;

- if (buffer->vaddr)
- return buffer->vaddr;
+ if (dma_buf_map_is_set(map))
+ goto out;

/*
* FIXME: The dependency on GEM here isn't required, we could
@@ -319,13 +325,14 @@ void *drm_client_buffer_vmap(struct drm_client_buffer *buffer)
* fd_install step out of the driver backend hooks, to make that
* final step optional for internal users.
*/
- ret = drm_gem_vmap(buffer->gem, &map);
+ ret = drm_gem_vmap(buffer->gem, map);
if (ret)
- return ERR_PTR(ret);
+ return ret;

- buffer->vaddr = map.vaddr;
+out:
+ *map_copy = *map;

- return map.vaddr;
+ return 0;
}
EXPORT_SYMBOL(drm_client_buffer_vmap);

@@ -339,10 +346,9 @@ EXPORT_SYMBOL(drm_client_buffer_vmap);
*/
void drm_client_buffer_vunmap(struct drm_client_buffer *buffer)
{
- struct dma_buf_map map = DMA_BUF_MAP_INIT_VADDR(buffer->vaddr);
+ struct dma_buf_map *map = &buffer->map;

- drm_gem_vunmap(buffer->gem, &map);
- buffer->vaddr = NULL;
+ drm_gem_vunmap(buffer->gem, map);
}
EXPORT_SYMBOL(drm_client_buffer_vunmap);

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 8697554ccd41..343a292f2c7c 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -394,7 +394,7 @@ static void drm_fb_helper_dirty_blit_real(struct drm_fb_helper *fb_helper,
unsigned int cpp = fb->format->cpp[0];
size_t offset = clip->y1 * fb->pitches[0] + clip->x1 * cpp;
void *src = fb_helper->fbdev->screen_buffer + offset;
- void *dst = fb_helper->buffer->vaddr + offset;
+ void *dst = fb_helper->buffer->map.vaddr + offset;
size_t len = (clip->x2 - clip->x1) * cpp;
unsigned int y;

@@ -416,7 +416,8 @@ static void drm_fb_helper_dirty_work(struct work_struct *work)
struct drm_clip_rect *clip = &helper->dirty_clip;
struct drm_clip_rect clip_copy;
unsigned long flags;
- void *vaddr;
+ struct dma_buf_map map;
+ int ret;

spin_lock_irqsave(&helper->dirty_lock, flags);
clip_copy = *clip;
@@ -429,8 +430,8 @@ static void drm_fb_helper_dirty_work(struct work_struct *work)

/* Generic fbdev uses a shadow buffer */
if (helper->buffer) {
- vaddr = drm_client_buffer_vmap(helper->buffer);
- if (IS_ERR(vaddr))
+ ret = drm_client_buffer_vmap(helper->buffer, &map);
+ if (ret)
return;
drm_fb_helper_dirty_blit_real(helper, &clip_copy);
}
@@ -2076,7 +2077,8 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
struct drm_framebuffer *fb;
struct fb_info *fbi;
u32 format;
- void *vaddr;
+ struct dma_buf_map map;
+ int ret;

drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n",
sizes->surface_width, sizes->surface_height,
@@ -2112,11 +2114,14 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
fb_deferred_io_init(fbi);
} else {
/* buffer is mapped for HW framebuffer */
- vaddr = drm_client_buffer_vmap(fb_helper->buffer);
- if (IS_ERR(vaddr))
- return PTR_ERR(vaddr);
+ ret = drm_client_buffer_vmap(fb_helper->buffer, &map);
+ if (ret)
+ return ret;
+ if (map.is_iomem)
+ fbi->screen_base = map.vaddr_iomem;
+ else
+ fbi->screen_buffer = map.vaddr;

- fbi->screen_buffer = vaddr;
/* Shamelessly leak the physical address to user-space */
#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
if (drm_leak_fbdev_smem && fbi->fix.smem_start == 0)
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 7aaea665bfc2..f07f2fb02e75 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -3,6 +3,7 @@
#ifndef _DRM_CLIENT_H_
#define _DRM_CLIENT_H_

+#include <linux/dma-buf-map.h>
#include <linux/lockdep.h>
#include <linux/mutex.h>
#include <linux/types.h>
@@ -141,9 +142,9 @@ struct drm_client_buffer {
struct drm_gem_object *gem;

/**
- * @vaddr: Virtual address for the buffer
+ * @map: Virtual address for the buffer
*/
- void *vaddr;
+ struct dma_buf_map map;

/**
* @fb: DRM framebuffer
@@ -155,7 +156,7 @@ struct drm_client_buffer *
drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format);
void drm_client_framebuffer_delete(struct drm_client_buffer *buffer);
int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect);
-void *drm_client_buffer_vmap(struct drm_client_buffer *buffer);
+int drm_client_buffer_vmap(struct drm_client_buffer *buffer, struct dma_buf_map *map);
void drm_client_buffer_vunmap(struct drm_client_buffer *buffer);

int drm_client_modeset_create(struct drm_client_dev *client);
--
2.28.0