RE: [PATCH net 2/3] net: cdc_mbim: send ZLP after max sized NTBs

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> -----Original Message-----
> From: Bjørn Mork [mailto:bjorn@xxxxxxx]
> 
> We normally avoid sending ZLPs by padding NTBs with a zero byte if the
> NTB is shorter than dwNtbOutMaxSize, resulting in a short USB packet
> instead of a ZLP.  But in the case where the NTB length is exactly
> dwNtbOutMaxSize and this is an exact multiplum of wMaxPacketSize, then
> we must send a ZLP.
> 
> This fixes an issue seen on a Sierra Wireless MC7710 device where the
> transmission would fail whenever we ended up padding the NTBs to max
> size.

If you add ZLP for NTBs of dwNtbOutMaxSize, you are heavily affecting CPU
load, increasing interrupt load by factor of 2 in high load traffic
scenario and possibly decreasing throughput for all other devices
which behaves correctly. 

Why should others pay for Sierra Wireless fault?

At least, do check VID/PID in usbnet and send ZLP only for malfunctioning 
devices.

Regards,
Alexey
��.n��������+%������w��{.n�����{���)��jg��������ݢj����G�������j:+v���w�m������w�������h�����٥



[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux