lkml.org 
[lkml]   [2019]   [Feb]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 3/3] pwm: core: add consumer device link
Date
Add a device link between the PWM consumer and the PWM provider. This
enforces the PWM user to get suspended before the PWM provider. It
allows proper synchronization of suspend/resume sequences: the PWM user
is responsible for properly stopping PWM, before the provider gets
suspended: see [1]. Add the device link in:
- pwm_get()
- devm_pwm_get()
- devm_of_pwm_get()
as it requires a reference to the device for the PWM consumer.

[1] https://lkml.org/lkml/2019/2/5/770

Suggested-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
drivers/pwm/core.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 1581f6a..2835e27 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -770,8 +770,13 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
int err;

/* look up via DT first */
- if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
- return of_pwm_get(dev->of_node, con_id);
+ if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) {
+ pwm = of_pwm_get(dev->of_node, con_id);
+ if (!IS_ERR(pwm))
+ device_link_add(dev, pwm->chip->dev,
+ DL_FLAG_AUTOREMOVE_CONSUMER);
+ return pwm;
+ }

/*
* We look up the provider in the static table typically provided by
@@ -851,6 +856,8 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
pwm->args.period = chosen->period;
pwm->args.polarity = chosen->polarity;

+ device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER);
+
return pwm;
}
EXPORT_SYMBOL_GPL(pwm_get);
@@ -943,6 +950,8 @@ struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
if (!IS_ERR(pwm)) {
*ptr = pwm;
devres_add(dev, ptr);
+ device_link_add(dev, pwm->chip->dev,
+ DL_FLAG_AUTOREMOVE_CONSUMER);
} else {
devres_free(ptr);
}
--
1.9.1
\
 
 \ /
  Last update: 2019-02-11 17:13    [W:0.046 / U:1.868 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site