From 8fd3b90300bec541806dac271de2fd44e2e4e2d2 Mon Sep 17 00:00:00 2001 From: Paul Kocialkowski Date: Thu, 15 Nov 2018 17:32:48 +0100 Subject: [PATCH] drm/fb-helper: Blacklist writeback when adding connectors to fbdev Writeback connectors do not produce any on-screen output and require special care for use. Such connectors are hidden from enumeration in DRM resources by default, but they are still picked-up by fbdev. This makes rather little sense since fbdev is not really adapted for dealing with writeback. Moreover, this is also a source of issues when userspace disables the CRTC (and associated plane) without detaching the CRTC from the connector (which is hidden by default). In this case, the connector is still using the CRTC, leading to am "enabled/connectors mismatch" and eventually the failure of the associated atomic commit. This situation happens with VC4 testing under IGT GPU Tools. Filter out writeback connectors in the fbdev helper to solve this. Signed-off-by: Paul Kocialkowski Reviewed-by: Boris Brezillon Reviewed-by: Maxime Ripard Tested-by: Maxime Ripard Fixes: 935774cd71fe ("drm: Add writeback connector type") Cc: # v4.19+ Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20181115163248.21168-1-paul.kocialkowski@bootlin.com --- drivers/gpu/drm/drm_fb_helper.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index a502f3e519fd..dd852a25d375 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -219,6 +219,9 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper) mutex_lock(&fb_helper->lock); drm_connector_list_iter_begin(dev, &conn_iter); drm_for_each_connector_iter(connector, &conn_iter) { + if (connector->connector_type == DRM_MODE_CONNECTOR_WRITEBACK) + continue; + ret = __drm_fb_helper_add_one_connector(fb_helper, connector); if (ret) goto fail;