drm/exynos: add check for the device power status

V2: Add mutex protection, while read.

The hdmi and mixer win_commit calls currently are
not checking the status of IP before updating the
respective registers, this patch adds this check.
Signed-off-by: Shirish S <s.shirish@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_hdmi.c

@@ -2163,6 +2163,13 @@ static void hdmi_commit(void *ctx)
 
 	DRM_DEBUG_KMS("[%d] %s\n", __LINE__, __func__);
 
+	mutex_lock(&hdata->hdmi_mutex);
+	if (!hdata->powered) {
+		mutex_unlock(&hdata->hdmi_mutex);
+		return;
+	}
+	mutex_unlock(&hdata->hdmi_mutex);
+
 	hdmi_conf_apply(hdata);
 }
 

drivers/gpu/drm/exynos/exynos_mixer.c

@@ -776,6 +776,13 @@ static void mixer_win_commit(void *ctx, int win)
 
 	DRM_DEBUG_KMS("[%d] %s, win: %d\n", __LINE__, __func__, win);
 
+	mutex_lock(&mixer_ctx->mixer_mutex);
+	if (!mixer_ctx->powered) {
+		mutex_unlock(&mixer_ctx->mixer_mutex);
+		return;
+	}
+	mutex_unlock(&mixer_ctx->mixer_mutex);
+
 	if (win > 1 && mixer_ctx->vp_enabled)
 		vp_video_buffer(mixer_ctx, win);
 	else