Opened 5 years ago

Closed 5 years ago

Last modified 4 years ago

#12356 closed defect (not_a_bug)

AR934x: ht_capab LDPC causing some devices not to associate

Reported by: unwired <mauermann@…> Owned by: developers
Priority: response-needed Milestone: Barrier Breaker 14.07
Component: kernel Version: Trunk
Keywords: Cc:


My Printer (HP Officejet Pro 8500A plus) cannot associate to the TP-Link TL-WDR3600 running OpenWrt trunk. With original TP-Link firmware this works fine. After manually removing ht_capab LDPC from /etc/config/wireless it works with OpenWrt too. However, an Android device is not affected.

I found some code in drivers/net/wireless/ath/ath9k/hw.c that probably disables LDPC for AR9330. Maybe AR934x is broken too?

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Change History (7)

comment:1 Changed 5 years ago by nbd

  • Priority changed from high to response-needed

please try latest trunk

comment:2 Changed 5 years ago by nbd

  • Resolution set to no_response
  • Status changed from new to closed

comment:3 Changed 5 years ago by anonymous

  • Resolution no_response deleted
  • Status changed from closed to reopened

Used AR9340 (OM2P-HS) together with an Epson SX525WD. The revision of OpenWrt is (trunk) r36335. Enabling LDPC makes it impossible to connect using the test device and disabling allows the device to connect.

comment:4 Changed 5 years ago by anonymous

It also happens with an QCA9558. The printer sends the information about not supporting LDPC in its HT capab during the probe req but says LDPC supported during the assoc req. It looks a little bit like the printer just copied the probe resp information (which had LDPC set to 1).

(sry, for using weird short forms, but the spam filter didn't allow me to send the post when using the full names)

comment:5 Changed 5 years ago by anonymous

Some printers seem to got a new fw update (e.g. HP 7510) which fixes the problem for them. Epson is still unusable because no such FW update exist.

The proprietary driver works because the initial management frames for the assoc req and so on are sent using legacy rates. The dhcp req works because the answer is sent using legacy rates after some failed attempts.

We are currently trying (unsuccessfully) to get in contact with the fw developers of Epson (it seems the technical people were replaced by standard support text blocks like "have you tried to turn it off and on again?").

comment:6 Changed 5 years ago by nbd

  • Resolution set to not_a_bug
  • Status changed from reopened to closed

Thanks for the information. I guess for everybody that can't get a new firmware, disabling LDPC is an acceptable workaround.
I don't see a good way to work around this in OpenWrt without breaking standard compliance or making things unnecessarily complex.

comment:7 Changed 4 years ago by jow

  • Milestone changed from Attitude Adjustment 12.09 to Barrier Breaker 14.07

Milestone Attitude Adjustment 12.09 deleted

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