Re: [RFC] mac80211: convert HW flags to unsigned long bitmap

[Johannes Berg <johannes@sipsolutions.net>]

On Tue, 2015-06-02 at 23:35 -0700, Joe Perches wrote:

> > +	IEEE80211_HW_HAS_RATE_CONTROL,
> > +	IEEE80211_HW_RX_INCLUDES_FCS,
> 
> It may be nicer to use specified bit numbers here.
> 
> It may make compatibility easier and maybe it should be
> written down that new entries are only to be added at
> the bottom of the enum and not inserted in the middle.

There's no reason for that, since it's pure kernel internal API any
renumbering of these bits is perfectly fine.

> This is similar to the broadcom tg3 driver, but a little different.
> 
> The mechanism in tg3 compared to ieee80211_hw is
> 	tg3_flag	ieee80211_hw_check
> 	tg3_flag_set	ieee80211_hw_set
> 	tg3_flag_clear	?
> 
> Would a ieee80211_hw_clear be useful?

See my reply to Julian.

> Would it be clearer without the _check?

Well, I thought it would read as

ieee80211_hw "check has_rate_control"

with this in a sense, for example.

> >  static ssize_t hwflags_read(struct file *file, char __user *user_buf,
> >  			    size_t count, loff_t *ppos)
> >  {
> []
> > +	for (i = 0; i < NUM_IEEE80211_HW_FLAGS; i++) {
> > +		if (test_bit(i, local->hw.flags))
> 
> Maybe use the ieee80211_hw_check() function?

Obviously that won't work. :) I could use the _ieee80211 one, but I'm
considering just getting rid of that one and inlining the test_bit into
the macro instead.

johannes