Mark screen buffers in system memory with FB_VIRTFB. Otherwise, fbdev deferred I/O marks mmap'ed areas of system memory with VM_IO. (There's an inverse relation ship between the two flags.)

For shadow buffers, also set the FB_READS_FAST hint.

v2: * updated commit description (Daniel) * added Fixes tag

Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Fixes: d536540f304c ("drm/fb-helper: Add generic fbdev emulation .fb_probe function") Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # v4.19+ --- drivers/gpu/drm/drm_fb_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index ed43b987d306..f15127a32f7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->fbops = &drm_fbdev_fb_ops; fbi->screen_size = sizes->surface_height * fb->pitches[0]; fbi->fix.smem_len = fbi->screen_size; + fbi->flags = FBINFO_DEFAULT;

drm_fb_helper_fill_info(fbi, fb_helper, sizes);

@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper, fbi->screen_buffer = vzalloc(fbi->screen_size); if (!fbi->screen_buffer) return -ENOMEM; + fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;

fbi->fbdefio = &drm_fbdev_defio; - fb_deferred_io_init(fbi); } else { /* buffer is mapped for HW framebuffer */ ret = drm_client_buffer_vmap(fb_helper->buffer, &map); if (ret) return ret; - if (map.is_iomem) + if (map.is_iomem) { fbi->screen_base = map.vaddr_iomem; - else + } else { fbi->screen_buffer = map.vaddr; + fbi->flags |= FBINFO_VIRTFB; + }

/* * Shamelessly leak the physical address to user-space. As