Re: v4.10-rc4 to v4.10-rc5: battery regression on Nokia N900

From: Guenter Roeck <linux@roeck-us.net>
To: Pavel Machek <pavel@ucw.cz>
Cc: Zhang Rui <rui.zhang@intel.com>,
	pali.rohar@gmail.com, sre@kernel.org,
	kernel list <linux-kernel@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	linux-omap@vger.kernel.org, tony@atomide.com, khilman@kernel.org,
	aaro.koskinen@iki.fi, ivo.g.dimitrov.75@gmail.com,
	patrikbachan@gmail.com, serge@hallyn.com, abcloriens@gmail.com,
	fabio.estevam@nxp.com
Subject: Re: v4.10-rc4 to v4.10-rc5: battery regression on Nokia N900
Date: Tue, 24 Jan 2017 06:30:39 -0800	[thread overview]
Message-ID: <44876c3d-158b-ecb3-2ae0-cd7cbf79ed29@roeck-us.net> (raw)
In-Reply-To: <20170124141548.GA14489@amd>

On 01/24/2017 06:15 AM, Pavel Machek wrote:
> Hi!
>
>>>>>> /sys files related to battery no longer appear. I beieve this has
>>>>>> something to do with it:
>>>>>>
>>>>>> [    2.374877] of_get_named_gpiod_flags: parsed 'reset-gpios' property
>>>>>> of node '/ocp@68000000/spi@48098000/tsc2005@0[0]' - status (0)
>>>>>> [    2.375946] input: TSC2005 touchscreen as
>>>>>> /devices/platform/68000000.ocp/48098000.spi/spi_master/spi1/spi1.0/input/input5
>>>>>> [    2.392120] rx51-battery: probe of n900-battery failed with error
>>>>>> -22
>>>>>
>>>>> Mystery solved:
>>>>>
>>>>> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
>>>>> index 3932f92..fe5ec82 100644
>>>>> --- a/drivers/hwmon/hwmon.c
>>>>> +++ b/drivers/hwmon/hwmon.c
>>>>> @@ -545,8 +545,10 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
>>>>> 	int i, j, err, id;
>>>>>
>>>>> 	/* Do not accept invalid characters in hwmon name attribute */
>>>>> -	if (name && (!strlen(name) || strpbrk(name, "-* \t\n")))
>>>>> +	if (name && (!strlen(name) || strpbrk(name, "-* \t\n"))) {
>>>>> +		printk("hwmon: Invalid character detected: %s\n", name);
>>>>> 		return ERR_PTR(-EINVAL);
>>>>> +	}
>>>>>
>>>>> 	id = ida_simple_get(&hwmon_ida, 0, 0, GFP_KERNEL);
>>>>> 	if (id < 0)
>>>>>
>>>>>
>>>>> pavel@n900:~$ dmesg | grep -5 Invalid
>>>>> [    0.829650] of_get_named_gpiod_flags: parsed 'gpio-reset' property
>>>>> of node '/ocp@68000000/i2c@48072000/tlv320aic3x@19[0]' - status (0)
>>>>> [    0.833831] tsl2563 2-0029: model 7, rev. 0
>>>>> [    0.837768] of_get_named_gpiod_flags: parsed 'enable-gpio' property
>>>>> of node '/ocp@68000000/i2c@48072000/lp5523@32[0]' - status (0)
>>>>> [    1.921417] omap_i2c 48072000.i2c: controller timed out
>>>>> [    2.056823] lp5523x 2-0032: lp5523 Programmable led chip found
>>>>> [    2.064147] hwmon: Invalid character detected: bq27200-0
>>>>
>>>> So the problem is really that the thermal driver needs to create a valid name.
>>>>
>>> Right.
>>>
>>> Before reverting, can you please try if this patch works or not?
>
>>> diff --git a/drivers/thermal/thermal_hwmon.c b/drivers/thermal/thermal_hwmon.c
>>> index c4a508a..0c6789f 100644
>>> --- a/drivers/thermal/thermal_hwmon.c
>>> +++ b/drivers/thermal/thermal_hwmon.c
>>> @@ -157,8 +157,8 @@ int thermal_add_hwmon_sysfs(struct thermal_zone_device *tz)
>>>
>>> 	INIT_LIST_HEAD(&hwmon->tz_list);
>>> 	strlcpy(hwmon->type, tz->type, THERMAL_NAME_LENGTH);
>>> -	hwmon->device = hwmon_device_register_with_info(NULL, hwmon->type,
>>> -							hwmon, NULL, NULL);
>>> +	hwmon->device = hwmon_device_register_with_info(NULL, NULL, NULL,
>>> +							NULL, NULL);
>>
>> This is wrong. The name should be converted to a valid name. Otherwise you would
>> still have to provide the name attribute yourself, and the resulting name would
>> still be invalid. A simple fix would be to add
>> 	strreplace(hwmon->type, '-', '_');
>> after strlcpy().
>
> Simple, yes. But that will change userland interface. Is it okay thing
> to do?

Yes, because the old name is invalid. Note that the new API also changes the
sysfs directory path. But, as mentioned separately, if providing valid
names is unacceptable for thermal drivers, the thermal subsystem will have
to stick with the old API (and I may create a patch to make the name attribute
mandatory for the new API to prevent people from defeating the purpose
of the conversion by not providing one).

Guenter