soc: qcom: rpmh: Dirt can only make you dirtier, not cleaner

Adding an item into the cache should never be able to make the cache
cleaner.  Use "|=" rather than "=" to update the dirty flag.
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Maulik Shah <mkshah@codeaurora.org> Thanks, Maulik
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Fixes: bb700067 ("soc: qcom: rpmh: Update dirty flag only when data changes")
Reported-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200417141531.1.Ia4b74158497213eabad7c3d474c50bfccb3f342e@changeidSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/soc/qcom/rpmh.c

@@ -151,10 +151,10 @@ static struct cache_req *cache_rpm_request(struct rpmh_ctrlr *ctrlr,
 		break;
 	}
 
-	ctrlr->dirty = (req->sleep_val != old_sleep_val ||
-			req->wake_val != old_wake_val) &&
-			req->sleep_val != UINT_MAX &&
-			req->wake_val != UINT_MAX;
+	ctrlr->dirty |= (req->sleep_val != old_sleep_val ||
+			 req->wake_val != old_wake_val) &&
+			 req->sleep_val != UINT_MAX &&
+			 req->wake_val != UINT_MAX;
 
 unlock:
 	spin_unlock_irqrestore(&ctrlr->cache_lock, flags);