diff mbox series

[v4,3/4] mfd: tps6586x: use devm-based power off handler

Message ID 20230327-tegra-pmic-reboot-v4-3-b24af219fb47@skidata.com
State Handled Elsewhere
Headers show
Series mfd: tps6586x: register restart handler | expand

Commit Message

Benjamin Bara April 13, 2023, 7:46 a.m. UTC 
From: Benjamin Bara <benjamin.bara@skidata.com>

Convert the power off handler to a devm-based power off handler.

Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com>
---
 drivers/mfd/tps6586x.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

Comments

Dmitry Osipenko April 13, 2023, 8:36 p.m. UTC | #1 
On 4/13/23 10:46, Benjamin Bara wrote:
> +static int tps6586x_power_off_handler(struct sys_off_data *data)
>  {
> -	if (tps6586x_clr_bits(tps6586x_dev, TPS6586X_SUPPLYENE, EXITSLREQ_BIT))
> -		return;
> +	struct device *tps6586x_dev = data->cb_data;
> +	int ret;
> +
> +	ret = tps6586x_clr_bits(tps6586x_dev, TPS6586X_SUPPLYENE, EXITSLREQ_BIT);
> +	if (ret)
> +		return ret;
>  
> -	tps6586x_set_bits(tps6586x_dev, TPS6586X_SUPPLYENE, SLEEP_MODE_BIT);
> +	return tps6586x_set_bits(tps6586x_dev, TPS6586X_SUPPLYENE, SLEEP_MODE_BIT);

Handlers must return NOTIFY_DONE or notifier_from_errno(). Sorry for
missing this previously.
Benjamin Bara April 14, 2023, 6:15 a.m. UTC | #2 
On Thu, 13 Apr 2023, 22:37 Dmitry Osipenko,
<dmitry.osipenko@collabora.com> wrote:
> Handlers must return NOTIFY_DONE or notifier_from_errno(). Sorry for
> missing this previously.

Thanks!

AFAIU, notifier_from_errno() sets NOTIFY_STOP_MASK, which stops
atomic_notifier_call_chain() immediately. So I think NOTIFY_DONE is the
only valid return value for sys_off handlers, to not skip others. So I
think letting sys_off_notify() [1] always return NOTIFY_DONE might be a
good idea.

If so, we could return a "notify return errno" (or also a "normal
errno") from the handler, which is checked, but then replaced to
NOTIFY_DONE, in [1]. This would enable us to have a common place to
check for failed handlers.

Handlers then should only return NOTIFY_DONE when they are skipped (e.g.
when the requested reboot mode is not supported by the handler).
Otherwise, I think ETIME, ENOSYS or ENOTSUPP might fit when the
communication was successful, a possible delay awaited, but the return
was still reached. What do you think?

Thanks and best regards,
Benjamin

[1] https://elixir.bootlin.com/linux/v6.3-rc6/source/kernel/reboot.c#L327
Dmitry Osipenko April 24, 2023, 10:42 a.m. UTC | #3 
On 4/14/23 09:15, Benjamin Bara wrote:
> On Thu, 13 Apr 2023, 22:37 Dmitry Osipenko,
> <dmitry.osipenko@collabora.com> wrote:
>> Handlers must return NOTIFY_DONE or notifier_from_errno(). Sorry for
>> missing this previously.
> 
> Thanks!
> 
> AFAIU, notifier_from_errno() sets NOTIFY_STOP_MASK, which stops
> atomic_notifier_call_chain() immediately. So I think NOTIFY_DONE is the
> only valid return value for sys_off handlers, to not skip others. So I
> think letting sys_off_notify() [1] always return NOTIFY_DONE might be a
> good idea.
> 
> If so, we could return a "notify return errno" (or also a "normal
> errno") from the handler, which is checked, but then replaced to
> NOTIFY_DONE, in [1]. This would enable us to have a common place to
> check for failed handlers.
> 
> Handlers then should only return NOTIFY_DONE when they are skipped (e.g.
> when the requested reboot mode is not supported by the handler).
> Otherwise, I think ETIME, ENOSYS or ENOTSUPP might fit when the
> communication was successful, a possible delay awaited, but the return
> was still reached. What do you think?

The behaviour may depend on a particular platform and driver. In general
and in case of this driver, it should be more reliable and cleaner to
abort the reboot on a error that shall never happen.
Benjamin Bara April 24, 2023, 12:07 p.m. UTC | #4 
On Mon, 24 Apr 2023 at 12:42, Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote:
> In general and in case of this driver, it should be more reliable and
> cleaner to abort the reboot on a error that shall never happen.

Thanks! Then I will drop my 4/6 of v5 [1].

[1] https://lore.kernel.org/all/20230327-tegra-pmic-reboot-v5-4-ab090e03284d@skidata.com/
diff mbox series

Patch

diff --git a/drivers/mfd/tps6586x.c b/drivers/mfd/tps6586x.c
index 2d947f3f606a..93f1bf440191 100644
--- a/drivers/mfd/tps6586x.c
+++ b/drivers/mfd/tps6586x.c
@@ -22,6 +22,7 @@ 
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/platform_device.h>
+#include <linux/reboot.h>
 #include <linux/regmap.h>
 #include <linux/of.h>
 
@@ -457,13 +458,16 @@  static const struct regmap_config tps6586x_regmap_config = {
 	.cache_type = REGCACHE_RBTREE,
 };
 
-static struct device *tps6586x_dev;
-static void tps6586x_power_off(void)
+static int tps6586x_power_off_handler(struct sys_off_data *data)
 {
-	if (tps6586x_clr_bits(tps6586x_dev, TPS6586X_SUPPLYENE, EXITSLREQ_BIT))
-		return;
+	struct device *tps6586x_dev = data->cb_data;
+	int ret;
+
+	ret = tps6586x_clr_bits(tps6586x_dev, TPS6586X_SUPPLYENE, EXITSLREQ_BIT);
+	if (ret)
+		return ret;
 
-	tps6586x_set_bits(tps6586x_dev, TPS6586X_SUPPLYENE, SLEEP_MODE_BIT);
+	return tps6586x_set_bits(tps6586x_dev, TPS6586X_SUPPLYENE, SLEEP_MODE_BIT);
 }
 
 static void tps6586x_print_version(struct i2c_client *client, int version)
@@ -559,9 +563,13 @@  static int tps6586x_i2c_probe(struct i2c_client *client)
 		goto err_add_devs;
 	}
 
-	if (pdata->pm_off && !pm_power_off) {
-		tps6586x_dev = &client->dev;
-		pm_power_off = tps6586x_power_off;
+	if (pdata->pm_off) {
+		ret = devm_register_power_off_handler(&client->dev, &tps6586x_power_off_handler,
+						      &client->dev);
+		if (ret) {
+			dev_err(&client->dev, "register power off handler failed: %d\n", ret);
+			goto err_add_devs;
+		}
 	}
 
 	return 0;