Subject: Request for stable backport: stmmac: Use correct values in TQS/RQS fields

From: Niklas Cassel <[email-masked]>
Date: Wed, 19 Dec 2018 10:55:16 +0100

Hello David,

I can observe a netdev watchdog timeout on kernel 4.14.78 when using stmmac
with multiple tx queues.

Backporting the following commit:

commit 52a76235d0c4dd259cd0df503afed4757c04ba1d                                                  
Author: Jose Abreu <[email-masked]>
Date:   Fri Oct 13 10:58:36 2017 +0100                                                           
                                                                                                 
    net: stmmac: Use correct values in TQS/RQS fields                                            

    Currently we are using all the available fifo size in RQS and                                
    TQS fields. This will not work correctly in multi-queues IP's                                
    because total fifo size must be splitted to the enabled queues.                              
                                                                                                 
    Correct this by computing the available fifo size per queue and                              
    setting the right value in TQS and RQS fields.                                               
                                                                                                 
    Signed-off-by: Jose Abreu <[email-masked]>                                             
    Cc: David S. Miller <[email-masked]>                                                    
    Cc: Joao Pinto <[email-masked]>
    Cc: Giuseppe Cavallaro <[email-masked]>                                              
    Cc: Alexandre Torgue <[email-masked]>                                               
    Signed-off-by: David S. Miller <[email-masked]>

resolves the issue.

The fix was first included in v4.15
$ git tag --contains 52a76235d0c4dd259cd0df503afed4757c04ba1d
v4.15
v4.15-rc1
v4.15-rc2

Could you please queue it up for 4.14 stable?

Kind regards,
Niklas