drm/vc4_kms: Protect hvs dereference on fkms

fkms has a null hvs pointer so this crashes. Protect against it

Signed-off-by: Dom Cobley <popcornmix@gmail.com>

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 190aade..064093a 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -354,7 +354,7 @@ static void vc4_atomic_commit_tail(struct drm_atomic_state *state)
        struct vc4_hvs_state *new_hvs_state;
        struct drm_crtc *crtc;
        struct vc4_hvs_state *old_hvs_state;
-       unsigned long max_clock_rate = clk_get_max_rate(hvs->core_clk);
+       unsigned long max_clock_rate = hvs ? clk_get_max_rate(hvs->core_clk) : 0;
        unsigned int channel;
        int i;