[OpenWrt-Devel] ath9k-htc init

[Jonas Gorski]

On Thu, Nov 26, 2015 at 2:07 PM, Alexey Brodkin
<Alexey.Brodkin at synopsys.com> wrote:
> Hi Jonas,
>
> On Mon, 2015-11-23 at 16:48 +0100, Jonas Gorski wrote:
>> On Mon, Nov 23, 2015 at 9:21 AM, Alexey Brodkin
>> <Alexey.Brodkin at synopsys.com> wrote:
>> > Hi Felix, Jonas,
>> >
>> > While playing with my AXS101 board and USB WI-Fi dongles I bumped in
>> > a couple of issues. Fortunately I found at least one dongle that
>> > works quite nice. That's TP-Link TL-WN721N (or its WN722N sibling)
>> > which is based on Atheros AR9271 chip even though it did require
>> > one unexpected tweak.
>> >
>> > For starters I just selected "kmod-ath9k-htc" in menuconfig and
>> > on boot saw USB device recognized, its firmware was loaded,
>> > "wifi detect" recognized it as well, see log below.
>> >
>> > But then "wlan0" interface was not created on "wifi" command.
>> >
>> > After some googling I somehow came to resolution that "hostapd"
>> > package installation fixes this problem. And indeed once I got
>> > image rebuilt with "CONFIG_PACKAGE_hostapd=y" all worked as expected
>> > and I was able to use my board as a Wi-Fi access point.
>> >
>> > So the question is if this is expected (requirement for "hostapd")
>> > [for "ath9k_htc"]?
>>
>> Yes, hostapd[-mini] (or wpad[-mini]) is required for AP mode, and
>> wpasupplicant or wpad for encrypted STA mode.
>
> Ooops I didn't realize that right away, indeed I'm trying to setup WiFi
> AP and hostAPD (which is really just "host AP Daemon") or alike is a must.
>
> The next question would be which option should I use then?
>  1) good olde HostAPD
>  2) its -mini sibling
>  3) wpad
>  4) its -mini sibling

OpenWrt default is wpad-mini for wifi capable devices (which is just a
unified binary of hostapd and wpasupplicant to prevent code
duplication and save space). The non-mini versions add support for
enterprisey stuff like radius athentication, which aren't needed for
most home setups.


>> > Another minor issue is that USB dongle gets recognized a bit late
>> > so that automatic "wifi detect" gets already executed and
>> > "/etc/config/wireless" isn't created. That requires manual execution of
>> > "wifi detect > /etc/config/wireless". Essentially extending delay in
>> > "package/base-files/files/etc/init.d/boot" makes a difference:
>> > ---------------------->8-------------------
>> >         # allow wifi modules time to settle
>> >         sleep 15 # instead of 1
>> > ---------------------->8-------------------
>> > but I'm not sure if we want to do that change for all devices.
>> > Then if there's a better way to make auto population of
>> > "/etc/config/wireless"?
>>
>> Likely the firmware is loaded asynchronously, so the _probe function
>> returns quickly. Our workaround in OpenWrt  for other drivers is to
>> make the _probe function wait for the firmware to have loaded. and
>> thus the wifi device registered in the linux kernel. This will ensure
>> the wifi subsystem knows about it when wifi detect is called. This
>> seems to be missing for ath9k-htc.
>
> May I get a reference to an example of that workaround?

see

package/kernel/mac80211/patches/861-brcmfmac-register-wiphy-s-during-module_init.patch
package/kernel/mac80211/patches/921-ath10k_init_devices_synchronously.patch
package/kernel/mac80211/patches/940-mwl8k_init_devices_synchronously.patch


Jonas
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