disp: msm: dp: change to internal lm bookkeeping

Previously we were updating internal layer mixer allocation
bookkeeping during every mode validation regardless of whether
the mixers were already designated in use, resulting in double
counting of in-use layer mixers.

This change prevents modification of these values if the given
connector's mode has already been previously validated so valid
modes can be returned properly.

Change-Id: Iea5dccfbc4087cc76f186101d38b605792326b16
Signed-off-by: Andrew Bartfeld <quic_abartfel@quicinc.com>

msm/dp/dp_display.c

@@ -2851,8 +2851,10 @@ static int dp_display_unprepare(struct dp_display *dp_display, void *panel)
 	/* log this as it results from user action of cable dis-connection */
 	DP_INFO("[OK]\n");
 end:
+	mutex_lock(&dp->accounting_lock);
 	dp->tot_lm_blks_in_use -= dp_panel->max_lm;
 	dp_panel->max_lm = 0;
+	mutex_unlock(&dp->accounting_lock);
 	dp_panel->deinit(dp_panel, flags);
 	mutex_unlock(&dp->session_lock);
 	SDE_EVT32_EXTERNAL(SDE_EVTLOG_FUNC_EXIT, dp->state);
@@ -3050,9 +3052,13 @@ static enum drm_mode_status dp_display_validate_mode(
 
 	mode_status = MODE_OK;
 
-	dp->tot_lm_blks_in_use -= dp_panel->max_lm;
-	dp_panel->max_lm = max(dp_panel->max_lm, dp_mode.lm_count);
-	dp->tot_lm_blks_in_use += dp_panel->max_lm;
+	if (!avail_res->num_lm_in_use) {
+		mutex_lock(&dp->accounting_lock);
+		dp->tot_lm_blks_in_use -= dp_panel->max_lm;
+		dp_panel->max_lm = max(dp_panel->max_lm, dp_mode.lm_count);
+		dp->tot_lm_blks_in_use += dp_panel->max_lm;
+		mutex_unlock(&dp->accounting_lock);
+	}
 
 end:
 	mutex_unlock(&dp->session_lock);