drm/i915/dp: Initialize the source OUI write timestamp always

If the source OUI DPCD register value matches the expected Intel OUI
value, the write timestamp doesn't get updated leaving it at the 0
initial value if the OUI wasn't written before. This can lead to an
incorrect wait duration in intel_dp_wait_source_oui(), since jiffies is
not inited to 0 in general (on a 32 bit system INITIAL_JIFFIES is set to
5 minutes ahead of wrap-around). Fix this by intializing the write
timestamp in the above case as well.

Reviewed-by: Ville Syrjälä <[email protected]>
Signed-off-by: Imre Deak <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: ideak

drivers/gpu/drm/i915/display/intel_dp.c

@@ -3418,8 +3418,11 @@ intel_edp_init_source_oui(struct intel_dp *intel_dp, bool careful)
 		if (drm_dp_dpcd_read(&intel_dp->aux, DP_SOURCE_OUI, buf, sizeof(buf)) < 0)
 			drm_err(&i915->drm, "Failed to read source OUI\n");
 
-		if (memcmp(oui, buf, sizeof(oui)) == 0)
+		if (memcmp(oui, buf, sizeof(oui)) == 0) {
+			/* Assume the OUI was written now. */
+			intel_dp->last_oui_write = jiffies;
 			return;
+		}
 	}
 
 	if (drm_dp_dpcd_write(&intel_dp->aux, DP_SOURCE_OUI, oui, sizeof(oui)) < 0)