From a5b44c4adb1699661d22e5152fb26885f30a2e4c Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Mon, 20 Mar 2023 16:07:44 +0100 Subject: [PATCH] drm/fbdev-generic: Always use shadow buffering Remove all codepaths that implement fbdev output directly on GEM buffers. Always allocate a shadow buffer in system memory and set up deferred I/O for mmap. The fbdev code that operated directly on GEM buffers was used by drivers based on GEM DMA helpers. Those drivers have been migrated to use fbdev-dma, a dedicated fbdev emulation for DMA memory. All remaining users of fbdev-generic require shadow buffering. Memory management of the remaining callers uses TTM, GEM SHMEM helpers or a variant of GEM DMA helpers that is incompatible with fbdev-dma. Therefore remove the unused codepaths from fbdev-generic and simplify the code. Using a shadow buffer with deferred I/O is probably the best case for most remaining callers. Some of the TTM-based drivers might benefit from a dedicated fbdev emulation that operates directly on the driver's video memory. Signed-off-by: Thomas Zimmermann Reviewed-by: Javier Martinez Canillas Acked-by: Zack Rusin Tested-by: Sui Jingfeng Link: https://patchwork.freedesktop.org/patch/msgid/20230320150751.20399-2-tzimmermann@suse.de --- drivers/gpu/drm/drm_fbdev_generic.c | 184 ++++++------------------------------ 1 file changed, 30 insertions(+), 154 deletions(-) diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c index 4d6325e..e48a8e8 100644 --- a/drivers/gpu/drm/drm_fbdev_generic.c +++ b/drivers/gpu/drm/drm_fbdev_generic.c @@ -11,16 +11,6 @@ #include -static bool drm_fbdev_use_shadow_fb(struct drm_fb_helper *fb_helper) -{ - struct drm_device *dev = fb_helper->dev; - struct drm_framebuffer *fb = fb_helper->fb; - - return dev->mode_config.prefer_shadow_fbdev || - dev->mode_config.prefer_shadow || - fb->funcs->dirty; -} - /* @user: 1=userspace, 0=fbcon */ static int drm_fbdev_fb_open(struct fb_info *info, int user) { @@ -46,115 +36,33 @@ static int drm_fbdev_fb_release(struct fb_info *info, int user) static void drm_fbdev_fb_destroy(struct fb_info *info) { struct drm_fb_helper *fb_helper = info->par; - void *shadow = NULL; + void *shadow = info->screen_buffer; if (!fb_helper->dev) return; - if (info->fbdefio) - fb_deferred_io_cleanup(info); - if (drm_fbdev_use_shadow_fb(fb_helper)) - shadow = info->screen_buffer; - + fb_deferred_io_cleanup(info); drm_fb_helper_fini(fb_helper); - - if (shadow) - vfree(shadow); - else if (fb_helper->buffer) - drm_client_buffer_vunmap(fb_helper->buffer); - + vfree(shadow); drm_client_framebuffer_delete(fb_helper->buffer); - drm_client_release(&fb_helper->client); + drm_client_release(&fb_helper->client); drm_fb_helper_unprepare(fb_helper); kfree(fb_helper); } -static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma) -{ - struct drm_fb_helper *fb_helper = info->par; - - if (drm_fbdev_use_shadow_fb(fb_helper)) - return fb_deferred_io_mmap(info, vma); - else if (fb_helper->dev->driver->gem_prime_mmap) - return fb_helper->dev->driver->gem_prime_mmap(fb_helper->buffer->gem, vma); - else - 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 drm_fbdev_fb_read(struct fb_info *info, char __user *buf, - size_t count, loff_t *ppos) -{ - ssize_t ret; - - if (drm_fbdev_use_iomem(info)) - ret = drm_fb_helper_cfb_read(info, buf, count, ppos); - else - ret = drm_fb_helper_sys_read(info, buf, count, ppos); - - return ret; -} - -static ssize_t drm_fbdev_fb_write(struct fb_info *info, const char __user *buf, - size_t count, loff_t *ppos) -{ - ssize_t ret; - - if (drm_fbdev_use_iomem(info)) - ret = drm_fb_helper_cfb_write(info, buf, count, ppos); - else - ret = drm_fb_helper_sys_write(info, buf, count, ppos); - - 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, .fb_open = drm_fbdev_fb_open, .fb_release = drm_fbdev_fb_release, + .fb_read = drm_fb_helper_sys_read, + .fb_write = drm_fb_helper_sys_write, + DRM_FB_HELPER_DEFAULT_OPS, + .fb_fillrect = drm_fb_helper_sys_fillrect, + .fb_copyarea = drm_fb_helper_sys_copyarea, + .fb_imageblit = drm_fb_helper_sys_imageblit, + .fb_mmap = fb_deferred_io_mmap, .fb_destroy = drm_fbdev_fb_destroy, - .fb_mmap = drm_fbdev_fb_mmap, - .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, }; /* @@ -169,7 +77,6 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper, struct drm_framebuffer *fb; struct fb_info *info; u32 format; - struct iosys_map map; int ret; drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n", @@ -197,44 +104,21 @@ static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper, drm_fb_helper_fill_info(info, fb_helper, sizes); - if (drm_fbdev_use_shadow_fb(fb_helper)) { - info->screen_buffer = vzalloc(info->screen_size); - if (!info->screen_buffer) - return -ENOMEM; - info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST; + info->screen_buffer = vzalloc(info->screen_size); + if (!info->screen_buffer) + return -ENOMEM; + info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST; - /* Set a default deferred I/O handler */ - fb_helper->fbdefio.delay = HZ / 20; - fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io; + info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer)); - info->fbdefio = &fb_helper->fbdefio; - ret = fb_deferred_io_init(info); - if (ret) - return ret; - } else { - /* buffer is mapped for HW framebuffer */ - ret = drm_client_buffer_vmap(fb_helper->buffer, &map); - if (ret) - return ret; - if (map.is_iomem) { - info->screen_base = map.vaddr_iomem; - } else { - info->screen_buffer = map.vaddr; - info->flags |= FBINFO_VIRTFB; - } - - /* - * Shamelessly leak the physical address to user-space. As - * page_to_phys() is undefined for I/O memory, warn in this - * case. - */ -#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM) - if (fb_helper->hint_leak_smem_start && info->fix.smem_start == 0 && - !drm_WARN_ON_ONCE(dev, map.is_iomem)) - info->fix.smem_start = - page_to_phys(virt_to_page(info->screen_buffer)); -#endif - } + /* Set a default deferred I/O handler */ + fb_helper->fbdefio.delay = HZ / 20; + fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io; + + info->fbdefio = &fb_helper->fbdefio; + ret = fb_deferred_io_init(info); + if (ret) + return ret; return 0; } @@ -318,18 +202,13 @@ static int drm_fbdev_fb_dirty(struct drm_fb_helper *helper, struct drm_clip_rect struct drm_device *dev = helper->dev; int ret; - if (!drm_fbdev_use_shadow_fb(helper)) - return 0; - /* Call damage handlers only if necessary */ if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2)) return 0; - if (helper->buffer) { - ret = drm_fbdev_damage_blit(helper, clip); - if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret)) - return ret; - } + ret = drm_fbdev_damage_blit(helper, clip); + if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret)) + return ret; if (helper->fb->funcs->dirty) { ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1); @@ -415,12 +294,9 @@ static const struct drm_client_funcs drm_fbdev_client_funcs = { * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves. * Simple drivers might use drm_mode_config_helper_suspend(). * - * Drivers that set the dirty callback on their framebuffer will get a shadow - * fbdev buffer that is blitted onto the real buffer. This is done in order to - * make deferred I/O work with all kinds of buffers. A shadow buffer can be - * requested explicitly by setting struct drm_mode_config.prefer_shadow or - * struct drm_mode_config.prefer_shadow_fbdev to true beforehand. This is - * required to use generic fbdev emulation with SHMEM helpers. + * In order to provide fixed mmap-able memory ranges, generic fbdev emulation + * uses a shadow buffer in system memory. The implementation blits the shadow + * fbdev buffer onto the real buffer in regular intervals. * * This function is safe to call even when there are no connectors present. * Setup will be retried on the next hotplug event. -- 2.7.4