This is a note to let you know that I've just added the patch titled

drm/fbdev: Clamp fbdev surface size if too large

to the 5.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summ...

The filename of the patch is: drm-fbdev-clamp-fbdev-surface-size-if-too-large.patch and it can be found in the queue-5.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From b693e42921e0220c0d564c55c6cdc680b0f85390 Mon Sep 17 00:00:00 2001

From: Thomas Zimmermann tzimmermann@suse.de Date: Tue, 5 Oct 2021 09:03:55 +0200 Subject: drm/fbdev: Clamp fbdev surface size if too large MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

From: Thomas Zimmermann tzimmermann@suse.de

commit b693e42921e0220c0d564c55c6cdc680b0f85390 upstream.

Clamp the fbdev surface size of the available maximumi height to avoid failing to init console emulation. An example error is shown below.

bad framebuffer height 2304, should be >= 768 && <= 768 [drm] Initialized simpledrm 1.0.0 20200625 for simple-framebuffer.0 on minor 0 simple-framebuffer simple-framebuffer.0: [drm] *ERROR* fbdev: Failed to setup generic emulation (ret=-22)

This is especially a problem with drivers that have very small screen sizes and cannot over-allocate at all.

v2: * reduce warning level (Ville)

Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Fixes: 11e8f5fd223b ("drm: Add simpledrm driver") Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com Reviewed-by: Alex Deucher alexander.deucher@amd.com Reported-by: Amanoel Dawod kernel@amanoeldawod.com Reported-by: Zoltán Kővágó dirty.ice.hu@gmail.com Reported-by: Michael Stapelberg michael+lkml@stapelberg.ch Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Maxime Ripard maxime@cerno.tech Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # v5.14+ Link: https://patchwork.freedesktop.org/patch/msgid/20211005070355.7680-1-tzimmerm... Signed-off-by: Dave Airlie airlied@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/drm_fb_helper.c | 6 ++++++ 1 file changed, 6 insertions(+)

--- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -1506,6 +1506,7 @@ static int drm_fb_helper_single_fb_probe { struct drm_client_dev *client = &fb_helper->client; struct drm_device *dev = fb_helper->dev; + struct drm_mode_config *config = &dev->mode_config; int ret = 0; int crtc_count = 0; struct drm_connector_list_iter conn_iter; @@ -1663,6 +1664,11 @@ static int drm_fb_helper_single_fb_probe /* Handle our overallocation */ sizes.surface_height *= drm_fbdev_overalloc; sizes.surface_height /= 100; + if (sizes.surface_height > config->max_height) { + drm_dbg_kms(dev, "Fbdev over-allocation too large; clamping height to %d\n", + config->max_height); + sizes.surface_height = config->max_height; + }

/* push down into drivers */ ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);

Patches currently in stable-queue which might be from tzimmermann@suse.de are

queue-5.14/drm-fbdev-clamp-fbdev-surface-size-if-too-large.patch