Re: [PATCH v5 11/20] ACPI: platform_profile: Add choices attribute for class interface

[Mario Limonciello]

On 11/8/2024 12:06, Armin Wolf wrote:
> Am 07.11.24 um 23:09 schrieb Mario Limonciello:
>
> > On 11/7/2024 02:28, Armin Wolf wrote:
> > > Am 07.11.24 um 07:02 schrieb Mario Limonciello:
> > >
> > > > The `choices` file will show all possible choices that a given platform
> > > > profile handler can support.
> > > >
> > > > Tested-by: Mark Pearson <mpearson-lenovo@xxxxxxxxx>
> > > > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> > > > ---
> > > > v5:
> > > >   * Fix kdoc
> > > >   * Add tag
> > > >   * Fix whitespace
> > > >   * Adjust mutex use
> > > > ---
> > > >   drivers/acpi/platform_profile.c | 65
> > > > +++++++++++++++++++++++++++++++++
> > > >   1 file changed, 65 insertions(+)
> > > >
> > > > diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/
> > > > platform_profile.c
> > > > index f605c2bd35c68..5e0bb91c5f451 100644
> > > > --- a/drivers/acpi/platform_profile.c
> > > > +++ b/drivers/acpi/platform_profile.c
> > > > @@ -25,6 +25,46 @@ static_assert(ARRAY_SIZE(profile_names) ==
> > > > PLATFORM_PROFILE_LAST);
> > > >
> > > >   static DEFINE_IDA(platform_profile_ida);
> > > >
> > > > +/**
> > > > + * _commmon_choices_show - Show the available profile choices
> > > > + * @choices: The available profile choices
> > > > + * @buf: The buffer to write to
> > > > + * Return: The number of bytes written
> > > > + */
> > > > +static ssize_t _commmon_choices_show(unsigned long choices, char *buf)
> > > > +{
> > > > +    int i, len = 0;
> > > > +
> > > > +    for_each_set_bit(i, &choices, PLATFORM_PROFILE_LAST) {
> > > > +        if (len == 0)
> > > > +            len += sysfs_emit_at(buf, len, "%s", profile_names[i]);
> > > > +        else
> > > > +            len += sysfs_emit_at(buf, len, " %s", profile_names[i]);
> > > > +    }
> > > > +    len += sysfs_emit_at(buf, len, "\n");
> > > > +
> > > > +    return len;
> > > > +}
> > > > +
> > > > +/**
> > > > + * _get_class_choices - Get the available profile choices for a
> > > > class device
> > > > + * @dev: The class device
> > > > + * @choices: Pointer to return the available profile choices
> > > > + * Return: The available profile choices
> > > > + */
> > > > +static int _get_class_choices(struct device *dev, unsigned long
> > > > *choices)
> > > > +{
> > > > +    struct platform_profile_handler *handler;
> > > > +    int i;
> > > > +
> > > > +    lockdep_assert_held(&profile_lock);
> > > > +    handler = dev_get_drvdata(dev);
> > > > +    for_each_set_bit(i, handler->choices, PLATFORM_PROFILE_LAST)
> > > > +        *choices |= BIT(i);
> > >
> > > Maybe just copying the bitmask would be enough here? In this case we
> > > could also drop
> > > this function as well.
> >
> > Right now this could work, but choices and the use of it has gone
> > through great lengths to ensure that once there are too many profiles
> > it automatically becomes a bigger variable.
> >
> >     unsigned long choices[BITS_TO_LONGS(PLATFORM_PROFILE_LAST)];
> >
> > So I would rather keep this as is.
> I think users of this function can do the locking themself and instead 
> use the functions from bitmap.h. Because _get_class_choices() will break 
> once "choices" becomes bigger.

I am thinking it's better to just switch explicitly to an 'unsigned 
long' and add a static check that all profiles fit.  If ever they don't 
fit, the code can be overhauled at that point.

And yes _get_class_choices can go away then, and this is a lot simpler.