Re: [RESEND PATCH v5 3/5] acerhdf: Use bang-bang thermal governor

Peter Feuerer
2014-12-04T07:11:44Z

Hi Darren,

thank you very much for your reply.

Darren Hart writes:

> On Fri, Nov 28, 2014 at 03:20:50PM +0100, Peter Feuerer wrote:
>> acerhdf has been doing an on-off fan control using hysteresis by
>> post-manipulating the outcome of thermal subsystem trip point handling.
>> This patch enables acerhdf to use the bang-bang governor, which is
>> intended for on-off controlled fans.
>>
>> Cc: platform-driver-x86@vger.kernel.org
>> Cc: Darren Hart <dvhart@infradead.org>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> CC: Zhang Rui <rui.zhang@intel.com>
>> Cc: Andreas Mohr <andi@lisas.de>
>> Cc: Javi Merino <javi.merino@arm.com>
>> Acked-and-tested-by: Borislav Petkov <bp@suse.de>
>> Signed-off-by: Peter Feuerer <peter@piie.net>
>> ---
>> drivers/platform/x86/Kconfig | 3 ++-
>> drivers/platform/x86/acerhdf.c | 36 +++++++++++++++++++++++++++++++-----
>> 2 files changed, 33 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
>> index a2eabe6..c173266 100644
>> --- a/drivers/platform/x86/Kconfig
>> +++ b/drivers/platform/x86/Kconfig
>> @@ -38,7 +38,8 @@ config ACER_WMI
>>
>> config ACERHDF
>> tristate "Acer Aspire One temperature and fan driver"
>> - depends on THERMAL && ACPI
>> + select THERMAL_GOV_BANG_BANG
>
> So we use select sparingly as it does implicit things.
>
> I checked the THERMAL_GOV_BANG_BANG Kconfig entry, and the help says acerhdf
> already depends on it (which it doesn't appear to). Any particular reason to add
> select here instead of adding it as a depends.
>
> Why did you drop THERMAL?

I had it like this in my first version of patches:
+ depends on THERMAL && ACPI && THERMAL_GOV_BANG_BANG

But after some discussion with lkml community we ended up with the select line and dropped THERMAL dependency, as it is implied by THEMAL_GOV_BANG_BANG. I'm not so experienced with Kconfig, so I must rely on the statements of the community in this case.

>> + depends on ACPI
>> ---help---
>> This is a driver for Acer Aspire One netbooks. It allows to access
>> the temperature sensor and to control the fan.
>> diff --git a/drivers/platform/x86/acerhdf.c b/drivers/platform/x86/acerhdf.c
>> index f30767f..7fe7dbf 100644
>> --- a/drivers/platform/x86/acerhdf.c
>> +++ b/drivers/platform/x86/acerhdf.c
>> @@ -50,7 +50,7 @@
>> */
>> #undef START_IN_KERNEL_MODE
>>
>> -#define DRV_VER "0.5.30"
>> +#define DRV_VER "0.7.0"
>>
>> /*
>> * According to the Atom N270 datasheet,
>> @@ -258,6 +258,14 @@ static const struct bios_settings_t bios_tbl[] = {
>>
>> static const struct bios_settings_t *bios_cfg __read_mostly;
>>
>> +/*
>> + * this struct is used to instruct thermal layer to use bang_bang instead of
>> + * default governor for acerhdf
>
> Please use sentence punctuation, particularly for block comments.

ok.

> /*
> * This struct...
> * default ... for acerhdf.
> */
>
>> + */
>> +static struct thermal_zone_params acerhdf_zone_params = {
>> + .governor_name = "bang_bang",
>> +};
>> +
>> static int acerhdf_get_temp(int *temp)
>> {
>> u8 read_temp;
>> @@ -439,6 +447,17 @@ static int acerhdf_get_trip_type(struct thermal_zone_device *thermal, int trip,
>> return 0;
>> }
>>
>> +static int acerhdf_get_trip_hyst(struct thermal_zone_device *thermal, int trip,
>> + unsigned long *temp)
>> +{
>> + if (trip != 0)
>> + return -EINVAL;
>> +
>> + *temp = fanon - fanoff;
>> +
>> + return 0;
>> +}
>> +
>> static int acerhdf_get_trip_temp(struct thermal_zone_device *thermal, int trip,
>> unsigned long *temp)
>> {
>> @@ -463,6 +482,7 @@ static struct thermal_zone_device_ops acerhdf_dev_ops = {
>> .get_mode = acerhdf_get_mode,
>> .set_mode = acerhdf_set_mode,
>> .get_trip_type = acerhdf_get_trip_type,
>> + .get_trip_hyst = acerhdf_get_trip_hyst,
>> .get_trip_temp = acerhdf_get_trip_temp,
>> .get_crit_temp = acerhdf_get_crit_temp,
>> };
>> @@ -515,9 +535,7 @@ static int acerhdf_set_cur_state(struct thermal_cooling_device *cdev,
>> }
>>
>> if (state == 0) {
>> - /* turn fan off only if below fanoff temperature */
>> - if ((cur_state == ACERHDF_FAN_AUTO) &&
>> - (cur_temp < fanoff))
>> + if (cur_state == ACERHDF_FAN_AUTO)
>> acerhdf_change_fanstate(ACERHDF_FAN_OFF);
>> } else {
>> if (cur_state == ACERHDF_FAN_OFF)
>> @@ -696,11 +714,19 @@ static int acerhdf_register_thermal(void)
>> return -EINVAL;
>>
>> thz_dev = thermal_zone_device_register("acerhdf", 1, 0, NULL,
>> - &acerhdf_dev_ops, NULL, 0,
>> + &acerhdf_dev_ops,
>> + &acerhdf_zone_params, 0,
>> (kernelmode) ? interval*1000 : 0);
>> if (IS_ERR(thz_dev))
>> return -EINVAL;
>>
>> + if (strcmp(thz_dev->governor->name,
>> + acerhdf_zone_params.governor_name)) {
>> + pr_err("Didn't get thermal governor %s, perhaps not compiled into thermal subsystem.\n",
>> + acerhdf_zone_params.governor_name);
>
> We've ensured it has to be compiled in, so that really can't be it. Right?

Yes, you are right, but if it is no real blocker for you, I'd like to keep this code in as I'm providing the acerhdf.c code in a separate package for debugging / testing too and people could use the code without the Kconfig.

--
kind regards,
--peter;