clocksource/drivers/mediatek: Optimize systimer irq clear flow on shutdown

mtk_syst_clkevt_shutdown is called after irq disabled in suspend flow,
clear any pending systimer irq when shutdown to avoid suspend aborted
due to timer irq pending

Also as for systimer in mediatek socs, there must be firstly enable
timer before clear systimer irq

Fixes: e3af677607d9("clocksource/drivers/timer-mediatek: Add support for system timer")
Signed-off-by: Fengquan Chen <fengquan.chen@mediatek.com>
Tested-by: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1617960162-1988-2-git-send-email-Fengquan.Chen@mediatek.com

diff --git a/drivers/clocksource/timer-mediatek.c b/drivers/clocksource/timer-mediatek.c
index ab63b95e414f58b980b0866a2140b1dc6dee81d3..7bcb4a3f26fb0ee7bf2fa3c4a916c9a31f5f4edd 100644 (file)
--- a/drivers/clocksource/timer-mediatek.c
+++ b/drivers/clocksource/timer-mediatek.c
@@ -60,9 +60,9 @@
  * SYST_CON_EN: Clock enable. Shall be set to
  *   - Start timer countdown.
  *   - Allow timeout ticks being updated.
- *   - Allow changing interrupt functions.
+ *   - Allow changing interrupt status,like clear irq pending.
  *
- * SYST_CON_IRQ_EN: Set to allow interrupt.
+ * SYST_CON_IRQ_EN: Set to enable interrupt.
  *
  * SYST_CON_IRQ_CLR: Set to clear interrupt.
  */
@@ -75,6 +75,7 @@ static void __iomem *gpt_sched_reg __read_mostly;
 static void mtk_syst_ack_irq(struct timer_of *to)
 {
        /* Clear and disable interrupt */
+       writel(SYST_CON_EN, SYST_CON_REG(to));
        writel(SYST_CON_IRQ_CLR | SYST_CON_EN, SYST_CON_REG(to));
 }
 
@@ -111,6 +112,9 @@ static int mtk_syst_clkevt_next_event(unsigned long ticks,
 
 static int mtk_syst_clkevt_shutdown(struct clock_event_device *clkevt)
 {
+       /* Clear any irq */
+       mtk_syst_ack_irq(to_timer_of(clkevt));
+
        /* Disable timer */
        writel(0, SYST_CON_REG(to_timer_of(clkevt)));