diff options
Diffstat (limited to 'drivers/gpu/drm/drm_fb_helper.c')
| -rw-r--r-- | drivers/gpu/drm/drm_fb_helper.c | 33 |
1 files changed, 31 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index a504a5e05676..9b111e846847 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -56,6 +56,25 @@ MODULE_PARM_DESC(drm_fbdev_overalloc, "Overallocation of the fbdev buffer (%) [default=" __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]"); +/* + * In order to keep user-space compatibility, we want in certain use-cases + * to keep leaking the fbdev physical address to the user-space program + * handling the fbdev buffer. + * This is a bad habit essentially kept into closed source opengl driver + * that should really be moved into open-source upstream projects instead + * of using legacy physical addresses in user space to communicate with + * other out-of-tree kernel modules. + * + * This module_param *should* be removed as soon as possible and be + * considered as a broken and legacy behaviour from a modern fbdev device. + */ +#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM) +static bool drm_leak_fbdev_smem = false; +module_param_unsafe(drm_leak_fbdev_smem, bool, 0600); +MODULE_PARM_DESC(fbdev_emulation, + "Allow unsafe leaking fbdev physical smem address [default=false]"); +#endif + static LIST_HEAD(kernel_fb_helper_list); static DEFINE_MUTEX(kernel_fb_helper_lock); @@ -2670,8 +2689,12 @@ __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper, info = fb_helper->fbdev; info->var.pixclock = 0; - /* don't leak any physical addresses to userspace */ - info->flags |= FBINFO_HIDE_SMEM_START; + /* Shamelessly allow physical address leaking to userspace */ +#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM) + if (!drm_leak_fbdev_smem) +#endif + /* don't leak any physical addresses to userspace */ + info->flags |= FBINFO_HIDE_SMEM_START; /* Need to drop locks to avoid recursive deadlock in * register_framebuffer. This is ok because the only thing left to do is @@ -3081,6 +3104,12 @@ int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_size = fb->height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size; fbi->screen_buffer = 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) + fbi->fix.smem_start = + page_to_phys(virt_to_page(fbi->screen_buffer)); +#endif strcpy(fbi->fix.id, "DRM emulated"); drm_fb_helper_fill_fix(fbi, fb->pitches[0], fb->format->depth); |