Low network throughput on i.MX28

[Stefan Wahren]

Hi Jörg,

> Jörg Krause <joerg.krause at embedded.rocks> hat am 15. Oktober 2016 um 10:46
> geschrieben:
> 
> 
> Thanks!
> 
> 
> For the record:
> 
> Note, this is the result for the wireless interface.
> 
> I got one of my custom boards running the legacy Linux Kernel 2.6.35
> officially supported from Freescale (NXP) and the bcmdhd driver from
> the Wiced project, where I get >20Mbps TCP throughput. The firmware
> version reported is:
> 
> # wl ver
> 5.90 RC115.2
> wl0: Apr 24 2014 14:08:41 version 5.90.195.89.24 FWID 01-bc2d0891
> 
> 
> I got it also running with the Linux Kernel 4.1.15 from Freescale [2],
> which is not officially supported for the i.MX28 target, with the
> latest bcmdhd version where I get <7Mbps TCP throughput (which is much
> the same I get with the brcmfmac driver). The firmware version reported
> is:
> 
> # wl ver
> 1.107 RC5.0
> wl0: Aug  8 2016 02:17:48 version 5.90.232 FWID 01-0
> 
> So, probably something is missing in the newer Kernel version, which is
> present in the legacy Kernel 2.6.35.
> 
> [1] http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/log/?h=
> imx_2.6.35_1.1.0
> [2] http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/log/?h=
> imx_4.1.15_1.0.0_ga

during implementation of DDR mode for the mmc driver [1] i noticed a performance
gap between the vendor kernel and mainline by a factor of 2. I expect that your
wireless interface is connected via SDIO.

Stefan

[1] -
http://linux-arm-kernel.infradead.narkive.com/GNkqjvo8/patch-rfc-0-3-mmc-mxs-mmc-implement-ddr-support