linux-kernel - Re: [PATCH 3/7] power: supply: core: fix HWMON temperature labels

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Message-ID: <20200403155310.GA19125@qmqm.qmqm.pl>
Date:   Fri, 3 Apr 2020 17:53:10 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     "Sebastian Reichel (maintainer:POWER SUPPLY CLASS/SUBSYSTEM and DRIVERS 
        ,blamed_fixes:1/1=100%)" <sebastian.reichel@...labora.com>,
        "Andrey Smirnov (blamed_fixes:1/1=100%)" <andrew.smirnov@...il.com>,
        "open list:POWER SUPPLY CLASS/SUBSYSTEM and DRIVERS" 
        <linux-pm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/7] power: supply: core: fix HWMON temperature labels

On Thu, Apr 02, 2020 at 11:29:32AM -0700, Guenter Roeck wrote:
> On 4/2/20 8:00 AM, Michał Mirosław wrote:
> > On Thu, Apr 02, 2020 at 07:52:19AM -0700, Guenter Roeck wrote:
> >> On 4/2/20 7:46 AM, Michał Mirosław wrote:
> >>> tempX_label files are swapped compared to what
> >>> power_supply_hwmon_temp_to_property() uses. Make them match.
> >>> While at it, make room for labeling other channels.
> >>>
> >>> Fixes: e67d4dfc9ff1 ("power: supply: Add HWMON compatibility layer")
> >>> Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> >>> ---
> >>>  drivers/power/supply/power_supply_hwmon.c | 14 +++++++++++++-
> >>>  1 file changed, 13 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/power/supply/power_supply_hwmon.c b/drivers/power/supply/power_supply_hwmon.c
> >>> index 75cf861ba492..83318a21fb52 100644
> >>> --- a/drivers/power/supply/power_supply_hwmon.c
> >>> +++ b/drivers/power/supply/power_supply_hwmon.c
> >>> @@ -43,6 +43,11 @@ static int power_supply_hwmon_curr_to_property(u32 attr)
> >>>  	}
> >>>  }
> >>>  
> >>> +static const char *const ps_temp_label[] = {
> >>> +	"temp",
> >>> +	"ambient temp",
> >>> +};
> >>> +
> >>>  static int power_supply_hwmon_temp_to_property(u32 attr, int channel)
> >>>  {
> >>>  	if (channel) {
> >>> @@ -144,7 +149,14 @@ static int power_supply_hwmon_read_string(struct device *dev,
> >>>  					  u32 attr, int channel,
> >>>  					  const char **str)
> >>>  {
> >>> -	*str = channel ? "temp" : "temp ambient";
> >>> +	switch (type) {
> >>> +	case hwmon_temp:
> >>> +		*str = ps_temp_label[channel];
> >>> +		break;
> >>> +	default:
> >>> +		break;
> >>
> >> That returns "no error" without setting *str, which is really asking for trouble.
> > 
> > This is carried over from earlier version. No bug though, but I'll add a
> > patch while I'm at it.
> > 
> 
> This is incorrect. The previous version does not check the type and always sets *str.
> 
> -	*str = channel ? "temp" : "temp ambient";

The function is called only for channels that have HWMON_T_LABEL set.
This is extended in later patches, though, so the type is going to be
required then. I'll split the addition so its more clear.

Best Regards,
Michał Mirosław