af_ath: don't use trash to configure interrupts

The WMI_ENABLE_INTR_CMDID can some time send empty package
to set interrupt to default value.
The problem is that ath_enable_intr_tgt is testing the
data pointer instead of dataleng variable.
We have never data == NULL case, even on zero size package.
(which is probably a bug too)

As result, FW was using some part of memory with undefined value
to configure interrupts. In most cases it was enabling SWBA interrupt
even if driver was trying to disable it.

In my tests, this issue was not really affecting STA or AP mode.

The only measurable difference i got on AP+STA mode. In this case
the FW was sending SWBA event to host at the channel switch in the
bgscan.

Possible effects of this issue:
- slow bgscan. EP3/EP4 have perfomance issue, extra traffic on will
make is slower.
- spreading our AP beacons on other channels.
- more ???

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>

diff --git a/target_firmware/wlan/if_ath.c b/target_firmware/wlan/if_ath.c
index d762989f1f1d50a3b5ea2dbec537a4f0e76262df..b31fbdb67e866d883732f14ca4171515015bbfbd 100755 (executable)
--- a/target_firmware/wlan/if_ath.c
+++ b/target_firmware/wlan/if_ath.c
@@ -1098,9 +1098,9 @@ static void ath_enable_intr_tgt(void *Context, A_UINT16 Command,
 {
        struct ath_softc_tgt *sc = (struct ath_softc_tgt *)Context;
        struct ath_hal *ah = sc->sc_ah;
-       a_uint32_t intr;
+       a_uint32_t intr = 0;
 
-       if (data)
+       if (datalen == 4)
                intr = (*(a_uint32_t *)data);
 
        intr = adf_os_ntohl(intr);