call trace on Khadas VIM Pro with AP6255 WiFi

Heiner Kallweit hkallweit1 at
Sun Jun 4 12:11:04 PDT 2017

Am 04.06.2017 um 17:59 schrieb crow:
> Hi,
> Posting to list as requested. I get call trace when using WiFi on Khadas VIM Pro, which comes with an AP6255. Firstly i wrote about this directly to Martin Blumenstingl, and he pointed me for this to post here.
> This looks like a bug in the meson-gx-mmc.c (SD/SDIO/eMMC) driver [1]. Martin last successful test was with kernel 2.11.
> How to reproduce this:
> mainline kernel 4.12.0-rc3 (using ArchLinuxARM arm8v generic rootfs)
> Khadas VIM Pro nvram file [2]
I have been in contact with others using AP6255-based SDIO WiFi with this driver. After the recent version of the driver
was released I didn't hear back from them so I assume WiFi is working fine for them.

The firmware image you use seems to be for Android. Not sure which firmware the others are using.
This might be a potential reason for the issue.

> Enable WiFI (connected to 5GHZ AP)
> just do an SSH to Khadas VIM Pro device and you will get these call trace [3] , eventually you get login prompt but it is very slow login. 
The log shows that first HW reports a failed write transfer (status 0x0100) and then an unexpected interrupt occurs (host->cmd being NULL).
Apart from the firmware the failed transfer might also be caused by e.g. a too high frequency.

Would be interesting to hear what's the latest kernel version (or even better: a bisect) working for you.

I'm using a Odroid-C2 where SDIO isn't available, so I'm not able to test.

> [1]
> [2]
> [3]

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