lkml.org 
[lkml]   [2019]   [Feb]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v4 3/3] pwm: core: add consumer device link
From
Date
On 2/19/19 9:55 AM, Uwe Kleine-König wrote:
> On Tue, Feb 19, 2019 at 09:46:32AM +0100, Fabrice Gasnier wrote:
>> On 2/18/19 6:22 PM, Uwe Kleine-König wrote:
>>> Hello,
>>>
>>> On Thu, Feb 14, 2019 at 11:25:51AM +0100, Fabrice Gasnier wrote:
>>>> 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:
>>>> - of_pwm_get()
>>>> - pwm_get()
>>>> - devm_*pwm_get() variants
>>>> 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>
>>>> ---
>>>> Changes in v4:
>>>> - rework error handling following Thierry's comments
>>>> - turn/split pr_debug() into dev_err()/pr_warn().
>>>>
>>>> Changes in v3:
>>>> - add struct device to of_get_pwm() arguments to handle device link from
>>>> there as discussed with Uwe.
>>>> ---
>>>> drivers/pwm/core.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++---
>>>> include/linux/pwm.h | 6 ++++--
>>>> 2 files changed, 51 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
>>>> index 1581f6a..64e10a6 100644
>>>> --- a/drivers/pwm/core.c
>>>> +++ b/drivers/pwm/core.c
>>>> @@ -636,8 +636,35 @@ static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
>>>> return ERR_PTR(-EPROBE_DEFER);
>>>> }
>>>>
>>>> +static struct device_link *pwm_device_link_add(struct device *dev,
>>>> + struct pwm_device *pwm)
>>>> +{
>>>> + struct device_link *dl;
>>>> +
>>>> + if (!dev) {
>>>> + /*
>>>> + * No device for the PWM consumer has been provided. It may
>>>> + * impact the PM sequence ordering: the PWM supplier may get
>>>> + * suspended before the consumer.
>>>> + */
>>>> + pr_warn("no consumer dev, can't create device link to %s\n",
>>>> + dev_name(pwm->chip->dev));
>>>
>>> Maybe use dev_warn(pwm->chip->dev, ...) ?
>>
>> Hi Uwe,
>>
>> I'm wondering a bit about this: In this case, the caller that doesn't
>> provide a struct device *, PWM provider isn't responsible for that. So I
>> just hope this wouldn't be miss-leading ?
>
> IMHO it's more the wording that might make the message misleading. If
> you use
>
> dev_warn(pwm->chip->dev, "No consumer device specified to create a device link to\n");
>
> that's completely fine in my eyes.

Thanks for the suggestion, I'll update this as well in v5.

Best regards,
Fabrice
>
> Best regards
> Uwe
>

\
 
 \ /
  Last update: 2019-02-19 10:55    [W:0.053 / U:15.160 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site