Patch "drivers/clocksource/timer-ti-dm: Don't call clk_get_rate() in stop function" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drivers/clocksource/timer-ti-dm: Don't call clk_get_rate() in stop function

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drivers-clocksource-timer-ti-dm-don-t-call-clk_get_r.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d7b0c29c8f17d70c3d5566b92dbdfa848bec8506
Author: Ivaylo Dimitrov <ivo.g.dimitrov.75@xxxxxxxxx>
Date:   Tue Oct 3 08:50:20 2023 +0300

    drivers/clocksource/timer-ti-dm: Don't call clk_get_rate() in stop function
    
    [ Upstream commit 12590d4d0e331d3cb9e6b3494515cd61c8a6624e ]
    
    clk_get_rate() might sleep, and that prevents dm-timer based PWM from being
    used from atomic context.
    
    Fix that by getting fclk rate in probe() and using a notifier in case rate
    changes.
    
    Fixes: af04aa856e93 ("ARM: OMAP: Move dmtimer driver out of plat-omap to drivers under clocksource")
    Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@xxxxxxxxx>
    Reviewed-by: Tony Lindgren <tony@xxxxxxxxxxx>
    Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/1696312220-11550-1-git-send-email-ivo.g.dimitrov.75@xxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/clocksource/timer-ti-dm.c b/drivers/clocksource/timer-ti-dm.c
index 09ab29cb7f641..5f60f6bd33866 100644
--- a/drivers/clocksource/timer-ti-dm.c
+++ b/drivers/clocksource/timer-ti-dm.c
@@ -140,6 +140,8 @@ struct dmtimer {
 	struct platform_device *pdev;
 	struct list_head node;
 	struct notifier_block nb;
+	struct notifier_block fclk_nb;
+	unsigned long fclk_rate;
 };
 
 static u32 omap_reserved_systimers;
@@ -253,8 +255,7 @@ static inline void __omap_dm_timer_enable_posted(struct dmtimer *timer)
 	timer->posted = OMAP_TIMER_POSTED;
 }
 
-static inline void __omap_dm_timer_stop(struct dmtimer *timer,
-					unsigned long rate)
+static inline void __omap_dm_timer_stop(struct dmtimer *timer)
 {
 	u32 l;
 
@@ -269,7 +270,7 @@ static inline void __omap_dm_timer_stop(struct dmtimer *timer,
 		 * Wait for functional clock period x 3.5 to make sure that
 		 * timer is stopped
 		 */
-		udelay(3500000 / rate + 1);
+		udelay(3500000 / timer->fclk_rate + 1);
 #endif
 	}
 
@@ -348,6 +349,21 @@ static int omap_timer_context_notifier(struct notifier_block *nb,
 	return NOTIFY_OK;
 }
 
+static int omap_timer_fclk_notifier(struct notifier_block *nb,
+				    unsigned long event, void *data)
+{
+	struct clk_notifier_data *clk_data = data;
+	struct dmtimer *timer = container_of(nb, struct dmtimer, fclk_nb);
+
+	switch (event) {
+	case POST_RATE_CHANGE:
+		timer->fclk_rate = clk_data->new_rate;
+		return NOTIFY_OK;
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
 static int omap_dm_timer_reset(struct dmtimer *timer)
 {
 	u32 l, timeout = 100000;
@@ -754,7 +770,6 @@ static int omap_dm_timer_stop(struct omap_dm_timer *cookie)
 {
 	struct dmtimer *timer;
 	struct device *dev;
-	unsigned long rate = 0;
 
 	timer = to_dmtimer(cookie);
 	if (unlikely(!timer))
@@ -762,10 +777,7 @@ static int omap_dm_timer_stop(struct omap_dm_timer *cookie)
 
 	dev = &timer->pdev->dev;
 
-	if (!timer->omap1)
-		rate = clk_get_rate(timer->fclk);
-
-	__omap_dm_timer_stop(timer, rate);
+	__omap_dm_timer_stop(timer);
 
 	pm_runtime_put_sync(dev);
 
@@ -1124,6 +1136,14 @@ static int omap_dm_timer_probe(struct platform_device *pdev)
 		timer->fclk = devm_clk_get(dev, "fck");
 		if (IS_ERR(timer->fclk))
 			return PTR_ERR(timer->fclk);
+
+		timer->fclk_nb.notifier_call = omap_timer_fclk_notifier;
+		ret = devm_clk_notifier_register(dev, timer->fclk,
+						 &timer->fclk_nb);
+		if (ret)
+			return ret;
+
+		timer->fclk_rate = clk_get_rate(timer->fclk);
 	} else {
 		timer->fclk = ERR_PTR(-ENODEV);
 	}