[RFC PATCH v2 0/2] nb8800 suspend/resume support

On 01/08/2017 18:32, Mason wrote:

I need suspend/resume support in the nb8800 driver.
On tango platforms, suspend loses all context (MMIO registers).
To make the task easy, we just close the device on suspend,
and open it again on resume. This requires properly resetting
the HW on resume.

Patch 1 moves all the HW init to nb8800_init()
Patch 2 adds suspend/resume support

I have now confirmed that the "flow control" issue I reported
in another thread has nothing to do with flow control per se.

The problem is that nb8800_pause_config() calls nb8800_dma_stop()
and when it does, RX is borked.

On a GigE switch:
[   21.444268] ENTER nb8800_pause_config
[   21.448604] rxcr=06100a8f pause_rx=1 pause_tx=0 pause=1 asym_pause=1
[   21.455020] nb8800 26000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx

In this case, pause_tx and RCR_FL match, so we skip the
silly dance.

On a FastE switch:
[   11.611613] ENTER nb8800_pause_config
[   11.615942] rxcr=06100a8f pause_rx=1 pause_tx=1 pause=1 asym_pause=0
[   11.825535] nb8800 26000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx

In this case pause_tx and RCR_FL don't match, so we hit
nb8800_dma_stop() and the HW block becomes deaf.

In conclusion, two issues I've been discussing:
A) RX wedged after ndo_close
B) flow control breaks on FastE switches
are in fact two symptoms of the same root issue.

Regards.