Though the unconditional enable/disable code is not a final solution, we don't want to run into a NULL pointer situation when window group doesn't link to its DC parent if the DC is disabled in Device Tree.

So this patch simply adds a check to make sure that window group has a valid parent before running into tegra_windowgroup_enable/disable.

Signed-off-by: Nicolin Chen nicoleotsuka@gmail.com --- drivers/gpu/drm/tegra/hub.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tegra/hub.c b/drivers/gpu/drm/tegra/hub.c index 8183e617bf6b..a2ef8f218d4e 100644 --- a/drivers/gpu/drm/tegra/hub.c +++ b/drivers/gpu/drm/tegra/hub.c @@ -149,7 +149,9 @@ int tegra_display_hub_prepare(struct tegra_display_hub *hub) for (i = 0; i < hub->soc->num_wgrps; i++) { struct tegra_windowgroup *wgrp = &hub->wgrps[i];

- tegra_windowgroup_enable(wgrp); + /* Skip orphaned window group whose parent DC is disabled */ + if (wgrp->parent) + tegra_windowgroup_enable(wgrp); }

return 0; @@ -166,7 +168,9 @@ void tegra_display_hub_cleanup(struct tegra_display_hub *hub) for (i = 0; i < hub->soc->num_wgrps; i++) { struct tegra_windowgroup *wgrp = &hub->wgrps[i];

- tegra_windowgroup_disable(wgrp); + /* Skip orphaned window group whose parent DC is disabled */ + if (wgrp->parent) + tegra_windowgroup_disable(wgrp); } }