wifi: mt7601u: add vnd_reset parameter to fix probe failure on Tenda U2

 

On certain MT7601U adapters, such as Tenda U2 and

other newer hardware revisions, driver initialization consistently fails

during probe with vendor request timeouts (-110 / -ETIMEDOUT):

  mt7601u 3-14:1.0: ASIC revision: 76010001 MAC revision: 76010500

  mt7601u 3-14:1.0: Firmware Version: 0.1.00 Build: 7640 Build time: 201302052146____

  mt7601u 3-14:1.0: Vendor request req:07 off:09a8 failed:-110

  mt7601u 3-14:1.0: Vendor request req:02 off:09a8 failed:-110

  mt7601u 3-14:1.0: Vendor request req:07 off:0734 failed:-110

  mt7601u 3-14:1.0: Vendor request req:42 off:0230 failed:-110

  mt7601u 3-14:1.0: probe with driver mt7601u failed with error -110

 

The failure occurs because mt7601u_load_firmware() unconditionally calls

mt7601u_vendor_reset() (MT_VEND_DEV_MODE_RESET) before uploading firmware

chunks. On these devices, issuing this vendor reset leaves the internal

MCU / FCE DMA engine in an unresponsive state after the first firmware

URB is submitted. As a result, reading MT_TX_CPU_FROM_FCE_CPU_DESC_IDX

(0x09a8) immediately times out.

Introduce a boolean module parameter 'vnd_reset' (default: false) to

make this vendor reset optional. When the vendor reset is skipped,

firmware upload succeeds and the wireless interface initializes normally.

 

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1716301

 

More issues with Tenda U2 and Linux:

- https://www.opena.tv/viewtopic.php?t=63919

- https://askubuntu.com/questions/1418850/the-problem-with-wi-fi-u2

- https://bbs.archlinux.org/viewtopic.php?id=224859

- https://www.reddit.com/r/archlinux/comments/1d6dfv5/mt7601u_usb_wifi_not_working/

 

Signed-off-by: Herman Semenoff <GermanAizek@yandex.ru>