On Thu, Oct 22, 2020 at 10:37:56AM +0200, Thomas Zimmermann wrote: > Hi > > On 22.10.20 10:05, Daniel Vetter wrote: > > On Tue, Oct 20, 2020 at 02:20:46PM +0200, Thomas Zimmermann wrote: > >> 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. > >> > >> 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 <tzimmerm...@suse.de> > >> Tested-by: Sam Ravnborg <s...@ravnborg.org> > >> --- > >> Documentation/gpu/todo.rst | 19 ++- > >> drivers/gpu/drm/bochs/bochs_kms.c | 1 - > >> drivers/gpu/drm/drm_fb_helper.c | 227 ++++++++++++++++++++++++++++-- > >> include/drm/drm_mode_config.h | 12 -- > >> 4 files changed, 230 insertions(+), 29 deletions(-) > >> > >> diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst > >> index 7e6fc3c04add..638b7f704339 100644 > >> --- a/Documentation/gpu/todo.rst > >> +++ b/Documentation/gpu/todo.rst > >> @@ -197,13 +197,28 @@ 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 <tzimmerm...@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 6212cd7cde1d..1d3180841778 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 +2026,206 @@ 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; > > > > Maybe a bit much a bikeshed, but I'd write this in terms of drm objects, > > like the dirty_blit function, using the dma_buf_map (instead of the > > fb_info parameter). And then instead of > > screen_base and screen_buffer suffixes give them _mem and _iomem suffixes. > > Screen_buffer can be a shadow buffer. Until the blit worker (see > drm_fb_helper_dirty_work() ) completes, it might be more up to date than > the real buffer that's stored in the client. > > The orignal fbdev code supported an fb_sync callback to synchronize with > outstanding screen updates (e.g., HW blit ops), but fb_sync is just > overhead here. Copying from screen_buffer or screen_base always returns > the most up-to-date image. > > > > > Same for write below. Or I'm not quite understanding why we do it like > > this here - I don't think this code will be used outside of the generic > > fbdev code, so we can always assume that drm_fb_helper->buffer is set up. > > It's similar as in the read case. If we write to the client's buffer, an > outstanding blit worker could write the now-outdated shadow buffer over > the user's newly written framebuffer data. > > Thinking about it, we might want to schedule the blit worker at the end > of each fb_write, so that the data makes it into the HW buffer in time.
Hm ok, makes some sense. I think there's some potential for cleanup if we add a dma_buf_map drm_fb_helper->uapi_map which points at the right thing always. That could then also the drm_fbdev_use_iomem() helper and make this all look really neat. But maybe a follow up clean up patch, if you're bored. As-is: Reviewed-by: Daniel Vetter <daniel.vet...@ffwll.ch> While looking at this I also noticed a potential small issue in an earlier patch. > > The other thing I think we need is some minimal testcases to make sure. > > The fbtest tool used way back seems to have disappeared, I couldn't find > > a copy of the source anywhere anymore. > > As discussed on IRC, I'll add some testcase to the igt test. I'll share > the link here when done. > > Best regards > Thomas > > > > > With all that: Acked-by: Daniel Vetter <daniel.vet...@ffwll.ch> > > > > Cheers, Daniel > > > >> + size_t alloc_size = min(count, PAGE_SIZE); > >> + ssize_t ret = 0; > >> + char *tmp; > >> + > >> + tmp = kmalloc(alloc_size, GFP_KERNEL); > >> + if (!tmp) > >> + return -ENOMEM; > >> + > >> + while (count) { > >> + size_t c = min(count, alloc_size); > >> + > >> + memcpy_fromio(tmp, src, c); > >> + if (copy_to_user(buf, tmp, c)) { > >> + ret = -EFAULT; > >> + break; > >> + } > >> + > >> + src += c; > >> + buf += c; > >> + ret += c; > >> + count -= c; > >> + } > >> + > >> + kfree(tmp); > >> + > >> + return ret; > >> +} > >> + > >> +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->state != FBINFO_STATE_RUNNING) > >> + return -EPERM; > >> + > >> + 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; > >> + u8 *tmp; > >> + > >> + tmp = kmalloc(alloc_size, GFP_KERNEL); > >> + if (!tmp) > >> + return -ENOMEM; > >> + > >> + while (count) { > >> + size_t c = min(count, alloc_size); > >> + > >> + if (copy_from_user(tmp, buf, c)) { > >> + ret = -EFAULT; > >> + break; > >> + } > >> + memcpy_toio(dst, tmp, c); > >> + > >> + dst += c; > >> + buf += c; > >> + ret += c; > >> + count -= c; > >> + } > >> + > >> + kfree(tmp); > >> + > >> + return ret; > >> +} > >> + > >> +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; > >> + > >> + if (info->state != FBINFO_STATE_RUNNING) > >> + return -EPERM; > >> + > >> + 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; > >> + > >> + if (err) > >> + return err; > >> + > >> + return ret; > >> +} > >> + > >> +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 +2233,11 @@ 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: > >> * > >> -- > >> 2.28.0 > >> > > > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5, 90409 Nürnberg, Germany > (HRB 36809, AG Nürnberg) > Geschäftsführer: Felix Imendörffer -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch