Status of the RTL8712 staging driver

Status of the RTL8712 staging driver

[Juan Carlos Garza Fernandez]

Hi Larry,

A long time ago, I asked you about the status of the realtek 8192cu
driver in the mainline and for access points and you told me that it
would be eventually implemented, which was indeed.

Now I have another question regarding the 8712 driver which has been
in staging forever.

In your opinion, are there any chances that it will be improved to
reach the mainline level?

If so, would it be possible to use it as an access point with HostAPD,
or is it limited by the firmware?

Best regards,

-- 
________________________________
Juan Carlos Garza

Re: Status of the RTL8712 staging driver

[Christian Lamparter]

On Tuesday, April 02, 2013 02:51:19 PM Juan Carlos Garza Fernandez wrote:
> Now I have another question regarding the 8712 driver which has been
> in staging forever.
> 
> In your opinion, are there any chances that it will be improved to
> reach the mainline level?
Hopefully yes. You can download a git-repository with the latest driver
from: <https://github.com/chunkeey/rtl8192su>

The latest incarnation "r92su" is currently the best bet on getting a
proper driver into the mainline. Unlike its predecessor rtl8192su it
uses cfg80211 directly (yes, unfortunately. it is a stand-alone driver
with no dependencies on rtlwifi).

what works with r92su:
	Station Mode & passive monitor
	802.11b/g/n (yes, HT is working - in both directions)
	WEP40/104,TKIP and CCMP (WPA and WPA2 works)
	Defragmentation
	QoS/WMM
	ERP

What isn't:
	AD-Hoc
	Fragmentation (also broken in r8712u... It would work, if the fw
	wouldn't override the sequence counter on out-going frames)
	SDIO transport
 
> If so, would it be possible to use it as an access point with HostAPD,
> or is it limited by the firmware?
Apparently there is a AP firmware. But you have to ask Realtek for the
right firmware.

Regards,
	Christian

Re: Status of the RTL8712 staging driver

[Larry Finger]

On 04/02/2013 12:41 PM, Christian Lamparter wrote:
> On Tuesday, April 02, 2013 02:51:19 PM Juan Carlos Garza Fernandez wrote:
>> Now I have another question regarding the 8712 driver which has been
>> in staging forever.
>>
>> In your opinion, are there any chances that it will be improved to
>> reach the mainline level?

Yes, r8712u has been in staging for a long time; however, it is not a matter of 
improving it. For a new wireless driver to be included in the main wireless 
directories, it must use mac80211. Making the change from the current softmac in 
r8712u to a mac80211-based driver is essentially a complete rewrite. As r8712u 
functions quite well in station mode, I have not felt inclined to rework it for 
AP mode, particularly when a user can obtain a functioning router/AP for about 
$30. I feel that my time is better spent converting the drivers for Realtek 
devices that are not currently in the kernel. That list includes the rtl8723ae 
driver in 3.8, the rtl8188ee driver that will be in 3.10, and 3 other drivers 
that I currently have on my todo list.

Larry

Re: Status of the RTL8712 staging driver

[Christian Lamparter]

On Tuesday, April 02, 2013 11:02:21 PM Larry Finger wrote:
> On 04/02/2013 12:41 PM, Christian Lamparter wrote:
> > On Tuesday, April 02, 2013 02:51:19 PM Juan Carlos Garza Fernandez wrote:
> >> Now I have another question regarding the 8712 driver which has been
> >> in staging forever.
> >>
> >> In your opinion, are there any chances that it will be improved to
> >> reach the mainline level?
> 
> Yes, r8712u has been in staging for a long time; however, it is not a matter of 
> improving it. For a new wireless driver to be included in the main wireless 
> directories, it must use mac80211. Making the change from the current softmac in 
> r8712u to a mac80211-based driver is essentially a complete rewrite., 
Oh, Joshua Roys had already investigated a mac80211 driver and abandoned
it since it is not possible:

"... Some differences from rtl8192se were eliminated, although all PHY/BB/RF
reg commands are still commented out.  *When any of those regs were accessed 
directly, the device would die*. When accessed through the IOCMD regs, the
firmware on the device would seem to disable automatic control of some 
important functions causing a large drop in receive sensitivity and general
performance." <http://marc.info/?l=linux-wireless&m=133644367402433>

The driver can't initialize the PHY and while the firmware has a command
to set the phy to a specified channel, you can't define the channel mode:
whenever it is supposed to be legacy, HT20, HT40+ or HT40-...

That's the reason why the new r92su now interfaces with cfg80211 instead
of mac80211. The *su firmware really forces you to use the "high-level"
commands it has for scan, connect, disconnect and join_ibss. 
(Furthermore, the scan/connect/... cmds also do the whole MLME work: probe,
(de-)auth, (dis-/re-)assoc and action for BA...  Unfortunately, mac80211
wants to do this a as well, so a mac80211 driver for rtl8192su would have
to discard all the mgmt frames from mac80211?!)   

> As r8712u functions quite well in station mode, I have not felt inclined to 
> rework it for AP mode, particularly when a user can obtain a functioning
> router/AP for about > $30. I feel that my time is better spent converting
> the drivers for Realtek devices that are not currently in the kernel. That
> list includes the rtl8723ae driver in 3.8, the rtl8188ee driver that will
> be in 3.10, and 3 other drivers that I currently have on my todo list.
Very true! (Is the RTL8812AU (Realtek's 11ac chip) also on the list?)

Regards,
	Christian

Re: Status of the RTL8712 staging driver

[Larry Finger]

On 04/03/2013 07:31 AM, Christian Lamparter wrote:
> Very true! (Is the RTL8812AU (Realtek's 11ac chip) also on the list?)

No, that one had not previously come to my attention. I see that chip will be in 
the TRENDnet TEW-805UB, but I do not believe it has yet shipped. In fact, the 
FCC filing was March 27, 2013 and it will not be allowed in the US for a while.

Larry