How to increase the value of AP_MAX_STATIONS on ubuntu pandaboard ES?

Hi,

I'm now working on the device driver of wl12xx on ubuntu running on pandabord-ES.
The kernel is linux-ti-omap4_3.2.0-1413.17.

My concern is to increase the number of WiFi TERMINALS that simultaneously connect to the MASTER mode wl12xx from 8 to 30.

What I did is:
Change the values in drivers/net/wireless/wl12xx/wl12xx.h as below:

# diff drivers/net/wireless/wl12xx/wl12xx.h.bak
drivers/net/wireless/wl12xx/wl12xx.h
142c142
< #define WL12XX_MAX_LINKS           12
---
> #define WL12XX_MAX_LINKS           34

238c238
< #define AP_MAX_STATIONS            8
---
> #define AP_MAX_STATIONS            30

The compilation of the driver was successful, but this driver produces error in wl1271_sdio_raw_read() defined in sdio.c.
More precisely, the error occurs at the line

                        ret = sdio_memcpy_fromio(func, buf, addr, len);

in
static void wl1271_sdio_raw_read(struct wl1271 *wl, int addr, void *buf, size_t len, bool fixed).

I also tried to increase the value AP_MAX_STATIONS to 9, but it also produced sdio error.

Any advices or suggestions are very welcome!
Thanks in advance,

Toshi