Low network throughput on i.MX28

[Jörg Krause]

Hi Stefan,

Am 15. Oktober 2016 10:59:41 MESZ, schrieb Stefan Wahren <stefan.wahren at i2se.com>:
>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.

Yes, it is. I had the suspicion that the MMC or the DMA driver is the bootleneck, too.

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

Looks like the patches might help. Have you tried SDIO wifi so far?

Jörg