[PATCH 1/2] drm/vc4: hdmi: Take our lock to reset the link

[maxime]

We access some fields protected by our internal mutex in
vc4_hdmi_reset_link() (saved_adjusted_mode, output_bpc, output_format)
and are calling functions that need to have that lock taken
(vc4_hdmi_supports_scrambling()).

However, the current code doesn't lock that mutex. Let's make sure it
does.

Fixes: 6bed2ea3cb38 ("drm/vc4: hdmi: Reset link on hotplug")
Signed-off-by: Maxime Ripard <max...@cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 596e311d6e58..9e549fa07467 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -349,27 +349,40 @@ static int vc4_hdmi_reset_link(struct drm_connector 
*connector,
        if (!crtc_state->active)
                return 0;
 
-       if (!vc4_hdmi_supports_scrambling(encoder))
+       mutex_lock(&vc4_hdmi->mutex);
+
+       if (!vc4_hdmi_supports_scrambling(encoder)) {
+               mutex_unlock(&vc4_hdmi->mutex);
                return 0;
+       }
 
        scrambling_needed = 
vc4_hdmi_mode_needs_scrambling(&vc4_hdmi->saved_adjusted_mode,
                                                           vc4_hdmi->output_bpc,
                                                           
vc4_hdmi->output_format);
-       if (!scrambling_needed)
+       if (!scrambling_needed) {
+               mutex_unlock(&vc4_hdmi->mutex);
                return 0;
+       }
 
        if (conn_state->commit &&
-           !try_wait_for_completion(&conn_state->commit->hw_done))
+           !try_wait_for_completion(&conn_state->commit->hw_done)) {
+               mutex_unlock(&vc4_hdmi->mutex);
                return 0;
+       }
 
        ret = drm_scdc_readb(connector->ddc, SCDC_TMDS_CONFIG, &config);
        if (ret < 0) {
                drm_err(drm, "Failed to read TMDS config: %d\n", ret);
+               mutex_unlock(&vc4_hdmi->mutex);
                return 0;
        }
 
-       if (!!(config & SCDC_SCRAMBLING_ENABLE) == scrambling_needed)
+       if (!!(config & SCDC_SCRAMBLING_ENABLE) == scrambling_needed) {
+               mutex_unlock(&vc4_hdmi->mutex);
                return 0;
+       }
+
+       mutex_unlock(&vc4_hdmi->mutex);
 
        /*
         * HDMI 2.0 says that one should not send scrambled data
-- 
2.37.3