drm/fb_helper: Support framebuffers in I/O memory

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@suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Tested-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201103093015.1063-11-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2020-11-03 10:30:15 +01:00
parent b4e7090c24
commit 222ec45f4c
4 changed files with 223 additions and 29 deletions

View File

@ -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@suse.de>, Daniel Vetter
Level: Advanced
drm_framebuffer_funcs and drm_mode_config_funcs.fb_create cleanup
-----------------------------------------------------------------

View File

@ -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;

View File

@ -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 = {

View File

@ -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:
*