linux-kernel - Re: [PATCH] regulator: core: silence warning: "VDD1: ramp

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Date:   Thu, 27 Oct 2016 19:45:32 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>,
        letux-kernel@...nphoenux.org
Subject: Re: [PATCH] regulator: core: silence warning: "VDD1: ramp_delay not set"

Hi,

> Am 27.10.2016 um 19:41 schrieb Matthias Kaehlcke <mka@...omium.org>:
> 
> El Thu, Oct 27, 2016 at 02:31:39PM +0200 H. Nikolaus Schaller ha dit:
> 
>> commit 73e705bf81ce ("regulator: core: Add set_voltage_time op")
>> 
>> introduced a new rdev_warn() if the ramp_delay is 0.
>> 
>> Apparently, on omap3/twl4030 platforms with dynamic voltage
>> management this results in non-ending spurious messages like
>> 
>> [  511.143066] VDD1: ramp_delay not set
>> [  511.662322] VDD1: ramp_delay not set
>> [  513.903625] VDD1: ramp_delay not set
>> [  514.222198] VDD1: ramp_delay not set
>> [  517.062835] VDD1: ramp_delay not set
>> [  517.382568] VDD1: ramp_delay not set
>> [  520.142791] VDD1: ramp_delay not set
>> [  520.502593] VDD1: ramp_delay not set
>> [  523.062896] VDD1: ramp_delay not set
>> [  523.362701] VDD1: ramp_delay not set
>> [  526.143035] VDD1: ramp_delay not set
>> 
>> I have observed this on GTA04 while it is reported to occur on
>> N900 as well: https://bugzilla.kernel.org/show_bug.cgi?id=178371
>> 
>> This patch makes the warning appear only in debugging mode.
>> 
>> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
>> ---
>> drivers/regulator/core.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
>> index 67426c0..5c1519b 100644
>> --- a/drivers/regulator/core.c
>> +++ b/drivers/regulator/core.c
>> @@ -2754,7 +2754,7 @@ static int _regulator_set_voltage_time(struct regulator_dev *rdev,
>> 		ramp_delay = rdev->desc->ramp_delay;
>> 
>> 	if (ramp_delay == 0) {
>> -		rdev_warn(rdev, "ramp_delay not set\n");
>> +		rdev_dbg(rdev, "ramp_delay not set\n");
>> 		return 0;
>> 	}
> 
> Sorry about that, I didn't run into this since in my tests ramp_delay
> was set :(

It may be that we have a rare exception. I didn't see it for example
on OMAP5 based boards.

> 
> Calling _regulator_set_voltage_time() with ramp_delay being zero is
> a common case, I think the message should be removed completely.

I'd have no problem if it is a debug feature, that is why I proposed
to not completely remove it unconditionally.

BR,
Nikolaus