13.07.2020 11:31, Chanwoo Choi пишет: > DEVFREQ supports the default governors like performance, powersave and also > allows the devfreq driver to add their own governor like tegra30-devfreq.c > according to their requirement. In result, some sysfs attributes are > useful or not useful. Prior to that the user can access all sysfs attributes > regardless of availability. > > So, clarify the access permission of sysfs attributes according to governor. > When adding the devfreq governor, can specify the available attribute > information by using DEVFREQ_GOV_ATTR_* constant variable. The user can > read or write the sysfs attributes in accordance to the specified attributes. > > /* Devfreq governor flags for attributes and features */ > [Definition for sysfs attributes] > - DEVFREQ_GOV_ATTR_GOVERNOR > - DEVFREQ_GOV_ATTR_AVAIL_GOVERNORS > - DEVFREQ_GOV_ATTR_AVAIL_FREQUENCIES > - DEVFREQ_GOV_ATTR_CUR_FREQ > - DEVFREQ_GOV_ATTR_TARGET_FREQ > - DEVFREQ_GOV_ATTR_MIN_FREQ > - DEVFREQ_GOV_ATTR_MAX_FREQ > - DEVFREQ_GOV_ATTR_TRANS_STAT > - DEVFREQ_GOV_ATTR_POLLING_INTERVAL > - DEVFREQ_GOV_ATTR_TIMER > > Also, the devfreq governor is able to have the specific flag as follows > in order to implement the specific feature. For example, Devfreq allows > user to change the governors on runtime via sysfs interface. > But, if devfreq device uses 'passive' governor, don't allow user to change > the governor. For this case, define the DEVFREQ_GOV_FLAT_IMMUTABLE > and set it to flag of passive governor. > > [Definition for governor flag] > - DEVFREQ_GOV_FLAG_IMMUTABLE > : If immutable flag is set, governor is never changeable to other governors. > - DEVFREQ_GOV_FLAG_IRQ_DRIVEN > : Devfreq core won't schedule polling work for this governor if value is set. > > [Table of governor flag for devfreq governors] > ------------------------------------------------------------------------------ > | simple | perfor | power | user | passive | tegra30 > | ondemand | mance | save | space| | > ------------------------------------------------------------------------------ > governor | O | O | O | O | O | O > available_governors | O | O | O | O | O | O > available_frequencies | O | O | O | O | O | O > cur_freq | O | O | O | O | O | O > target_freq | O | O | O | O | O | O > min_freq | O | O | O | O | O | O > max_freq | O | O | O | O | O | O > trans_stat | O | O | O | O | O | O > -------------------------------------------------------- > polling_interval | O | X | X | X | X | O > timer | O | X | X | X | X | X > ------------------------------------------------------------------------------ > immutable | X | X | X | X | O | O > interrupt_driven | X(polling)| X | X | X | X | O (irq) > ------------------------------------------------------------------------------ > > Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx> > --- Hello, Chanwoo! I tested this series on NVIDIA Tegra30 and everything working fine! Reviewed-by: Dmitry Osipenko <digetx@xxxxxxxxx> Tested-by: Dmitry Osipenko <digetx@xxxxxxxxx> BTW, I'm curious what do you think about hiding the unsupported debugfs attributes per-device instead of returning the -EACCES?
