[PATCH v7 10/10] drm/fb_helper: Support framebuffers in I/O memory
Thomas Zimmermann
tzimmermann at suse.de
Tue Nov 3 09:30:15 UTC 2020
At least sparc64 requires I/O-specific access to framebuffers. This
patch updates the fbdev console accordingly.
For drivers with direct access to the framebuffer memory, the callback
functions in struct fb_ops test for the type of memory and call the rsp
fb_sys_ of fb_cfb_ functions. Read and write operations are implemented
internally by DRM's fbdev helper.
For drivers that employ a shadow buffer, fbdev's blit function retrieves
the framebuffer address as struct dma_buf_map, and uses dma_buf_map
interfaces to access the buffer.
The bochs driver on sparc64 uses a workaround to flag the framebuffer as
I/O memory and avoid a HW exception. With the introduction of struct
dma_buf_map, this is not required any longer. The patch removes the rsp
code from both, bochs and fbdev.
v7:
* use min_t(size_t,) (kernel test robot)
* return the number of bytes read/written, if any (fbdev testcase)
v5:
* implement fb_read/fb_write internally (Daniel, Sam)
v4:
* move dma_buf_map changes into separate patch (Daniel)
* TODO list: comment on fbdev updates (Daniel)
Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Reviewed-by: Sam Ravnborg <sam at ravnborg.org>
Tested-by: Sam Ravnborg <sam at ravnborg.org>
---
Documentation/gpu/todo.rst | 19 ++-
drivers/gpu/drm/bochs/bochs_kms.c | 1 -
drivers/gpu/drm/drm_fb_helper.c | 220 ++++++++++++++++++++++++++++--
include/drm/drm_mode_config.h | 12 --
4 files changed, 223 insertions(+), 29 deletions(-)
diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index 59f63f1d7680..acca232b025b 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -201,13 +201,28 @@ Convert drivers to use drm_fbdev_generic_setup()
------------------------------------------------
Most drivers can use drm_fbdev_generic_setup(). Driver have to implement
-atomic modesetting and GEM vmap support. Current generic fbdev emulation
-expects the framebuffer in system memory (or system-like memory).
+atomic modesetting and GEM vmap support. Historically, generic fbdev emulation
+expected the framebuffer in system memory or system-like memory. By employing
+struct dma_buf_map, drivers with frambuffers in I/O memory can be supported
+as well.
Contact: Maintainer of the driver you plan to convert
Level: Intermediate
+Reimplement functions in drm_fbdev_fb_ops without fbdev
+-------------------------------------------------------
+
+A number of callback functions in drm_fbdev_fb_ops could benefit from
+being rewritten without dependencies on the fbdev module. Some of the
+helpers could further benefit from using struct dma_buf_map instead of
+raw pointers.
+
+Contact: Thomas Zimmermann <tzimmermann at suse.de>, Daniel Vetter
+
+Level: Advanced
+
+
drm_framebuffer_funcs and drm_mode_config_funcs.fb_create cleanup
-----------------------------------------------------------------
diff --git a/drivers/gpu/drm/bochs/bochs_kms.c b/drivers/gpu/drm/bochs/bochs_kms.c
index 13d0d04c4457..853081d186d5 100644
--- a/drivers/gpu/drm/bochs/bochs_kms.c
+++ b/drivers/gpu/drm/bochs/bochs_kms.c
@@ -151,7 +151,6 @@ int bochs_kms_init(struct bochs_device *bochs)
bochs->dev->mode_config.preferred_depth = 24;
bochs->dev->mode_config.prefer_shadow = 0;
bochs->dev->mode_config.prefer_shadow_fbdev = 1;
- bochs->dev->mode_config.fbdev_use_iomem = true;
bochs->dev->mode_config.quirk_addfb_prefer_host_byte_order = true;
bochs->dev->mode_config.funcs = &bochs_mode_funcs;
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index a0d88130fedb..01ba1da28511 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -372,24 +372,22 @@ static void drm_fb_helper_resume_worker(struct work_struct *work)
}
static void drm_fb_helper_dirty_blit_real(struct drm_fb_helper *fb_helper,
- struct drm_clip_rect *clip)
+ struct drm_clip_rect *clip,
+ struct dma_buf_map *dst)
{
struct drm_framebuffer *fb = fb_helper->fb;
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->map.vaddr + offset;
size_t len = (clip->x2 - clip->x1) * cpp;
unsigned int y;
- for (y = clip->y1; y < clip->y2; y++) {
- if (!fb_helper->dev->mode_config.fbdev_use_iomem)
- memcpy(dst, src, len);
- else
- memcpy_toio((void __iomem *)dst, src, len);
+ dma_buf_map_incr(dst, offset); /* go to first pixel within clip rect */
+ for (y = clip->y1; y < clip->y2; y++) {
+ dma_buf_map_memcpy_to(dst, src, len);
+ dma_buf_map_incr(dst, fb->pitches[0]);
src += fb->pitches[0];
- dst += fb->pitches[0];
}
}
@@ -417,8 +415,9 @@ static void drm_fb_helper_dirty_work(struct work_struct *work)
ret = drm_client_buffer_vmap(helper->buffer, &map);
if (ret)
return;
- drm_fb_helper_dirty_blit_real(helper, &clip_copy);
+ drm_fb_helper_dirty_blit_real(helper, &clip_copy, &map);
}
+
if (helper->fb->funcs->dirty)
helper->fb->funcs->dirty(helper->fb, NULL, 0, 0,
&clip_copy, 1);
@@ -2027,6 +2026,199 @@ static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
return -ENODEV;
}
+static bool drm_fbdev_use_iomem(struct fb_info *info)
+{
+ struct drm_fb_helper *fb_helper = info->par;
+ struct drm_client_buffer *buffer = fb_helper->buffer;
+
+ return !drm_fbdev_use_shadow_fb(fb_helper) && buffer->map.is_iomem;
+}
+
+static ssize_t fb_read_screen_base(struct fb_info *info, char __user *buf, size_t count,
+ loff_t pos)
+{
+ const char __iomem *src = info->screen_base + pos;
+ size_t alloc_size = min(count, PAGE_SIZE);
+ ssize_t ret = 0;
+ int err = 0;
+ char *tmp;
+
+ tmp = kmalloc(alloc_size, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ while (count) {
+ size_t c = min_t(size_t, count, alloc_size);
+
+ memcpy_fromio(tmp, src, c);
+ if (copy_to_user(buf, tmp, c)) {
+ err = -EFAULT;
+ break;
+ }
+
+ src += c;
+ buf += c;
+ ret += c;
+ count -= c;
+ }
+
+ kfree(tmp);
+
+ return ret ? ret : err;
+}
+
+static ssize_t fb_read_screen_buffer(struct fb_info *info, char __user *buf, size_t count,
+ loff_t pos)
+{
+ const char *src = info->screen_buffer + pos;
+
+ if (copy_to_user(buf, src, count))
+ return -EFAULT;
+
+ return count;
+}
+
+static ssize_t drm_fbdev_fb_read(struct fb_info *info, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ loff_t pos = *ppos;
+ size_t total_size;
+ ssize_t ret;
+
+ if (info->screen_size)
+ total_size = info->screen_size;
+ else
+ total_size = info->fix.smem_len;
+
+ if (pos >= total_size)
+ return 0;
+ if (count >= total_size)
+ count = total_size;
+ if (total_size - count < pos)
+ count = total_size - pos;
+
+ if (drm_fbdev_use_iomem(info))
+ ret = fb_read_screen_base(info, buf, count, pos);
+ else
+ ret = fb_read_screen_buffer(info, buf, count, pos);
+
+ if (ret > 0)
+ *ppos += ret;
+
+ return ret;
+}
+
+static ssize_t fb_write_screen_base(struct fb_info *info, const char __user *buf, size_t count,
+ loff_t pos)
+{
+ char __iomem *dst = info->screen_base + pos;
+ size_t alloc_size = min(count, PAGE_SIZE);
+ ssize_t ret = 0;
+ int err = 0;
+ u8 *tmp;
+
+ tmp = kmalloc(alloc_size, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ while (count) {
+ size_t c = min_t(size_t, count, alloc_size);
+
+ if (copy_from_user(tmp, buf, c)) {
+ err = -EFAULT;
+ break;
+ }
+ memcpy_toio(dst, tmp, c);
+
+ dst += c;
+ buf += c;
+ ret += c;
+ count -= c;
+ }
+
+ kfree(tmp);
+
+ return ret ? ret : err;
+}
+
+static ssize_t fb_write_screen_buffer(struct fb_info *info, const char __user *buf, size_t count,
+ loff_t pos)
+{
+ char *dst = info->screen_buffer + pos;
+
+ if (copy_from_user(dst, buf, count))
+ return -EFAULT;
+
+ return count;
+}
+
+static ssize_t drm_fbdev_fb_write(struct fb_info *info, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ loff_t pos = *ppos;
+ size_t total_size;
+ ssize_t ret;
+ int err = 0;
+
+ if (info->screen_size)
+ total_size = info->screen_size;
+ else
+ total_size = info->fix.smem_len;
+
+ if (pos > total_size)
+ return -EFBIG;
+ if (count > total_size) {
+ err = -EFBIG;
+ count = total_size;
+ }
+ if (total_size - count < pos) {
+ if (!err)
+ err = -ENOSPC;
+ count = total_size - pos;
+ }
+
+ /*
+ * Copy to framebuffer even if we already logged an error. Emulates
+ * the behavior of the original fbdev implementation.
+ */
+ if (drm_fbdev_use_iomem(info))
+ ret = fb_write_screen_base(info, buf, count, pos);
+ else
+ ret = fb_write_screen_buffer(info, buf, count, pos);
+
+ if (ret > 0)
+ *ppos += ret;
+
+ return ret ? ret : err;
+}
+
+static void drm_fbdev_fb_fillrect(struct fb_info *info,
+ const struct fb_fillrect *rect)
+{
+ if (drm_fbdev_use_iomem(info))
+ drm_fb_helper_cfb_fillrect(info, rect);
+ else
+ drm_fb_helper_sys_fillrect(info, rect);
+}
+
+static void drm_fbdev_fb_copyarea(struct fb_info *info,
+ const struct fb_copyarea *area)
+{
+ if (drm_fbdev_use_iomem(info))
+ drm_fb_helper_cfb_copyarea(info, area);
+ else
+ drm_fb_helper_sys_copyarea(info, area);
+}
+
+static void drm_fbdev_fb_imageblit(struct fb_info *info,
+ const struct fb_image *image)
+{
+ if (drm_fbdev_use_iomem(info))
+ drm_fb_helper_cfb_imageblit(info, image);
+ else
+ drm_fb_helper_sys_imageblit(info, image);
+}
+
static const struct fb_ops drm_fbdev_fb_ops = {
.owner = THIS_MODULE,
DRM_FB_HELPER_DEFAULT_OPS,
@@ -2034,11 +2226,11 @@ static const struct fb_ops drm_fbdev_fb_ops = {
.fb_release = drm_fbdev_fb_release,
.fb_destroy = drm_fbdev_fb_destroy,
.fb_mmap = drm_fbdev_fb_mmap,
- .fb_read = drm_fb_helper_sys_read,
- .fb_write = drm_fb_helper_sys_write,
- .fb_fillrect = drm_fb_helper_sys_fillrect,
- .fb_copyarea = drm_fb_helper_sys_copyarea,
- .fb_imageblit = drm_fb_helper_sys_imageblit,
+ .fb_read = drm_fbdev_fb_read,
+ .fb_write = drm_fbdev_fb_write,
+ .fb_fillrect = drm_fbdev_fb_fillrect,
+ .fb_copyarea = drm_fbdev_fb_copyarea,
+ .fb_imageblit = drm_fbdev_fb_imageblit,
};
static struct fb_deferred_io drm_fbdev_defio = {
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index 5ffbb4ed5b35..ab424ddd7665 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -877,18 +877,6 @@ struct drm_mode_config {
*/
bool prefer_shadow_fbdev;
- /**
- * @fbdev_use_iomem:
- *
- * Set to true if framebuffer reside in iomem.
- * When set to true memcpy_toio() is used when copying the framebuffer in
- * drm_fb_helper.drm_fb_helper_dirty_blit_real().
- *
- * FIXME: This should be replaced with a per-mapping is_iomem
- * flag (like ttm does), and then used everywhere in fbdev code.
- */
- bool fbdev_use_iomem;
-
/**
* @quirk_addfb_prefer_xbgr_30bpp:
*
--
2.29.0
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