[PATCH] staging: rtl8723au: hal: check BT_Active and BT_State with correct bit pattern

[PATCH] staging: rtl8723au: hal: check BT_Active and BT_State with correct bit pattern

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

BT_Active and BT_State are being masked with 0x00ffffff so it the subsequent
comparisons with 0xffffffff are therefore a buggy check.  Instead, check them
against 0x00ffffff.

Unfortunately I couldn't find a datasheet or hardware to see if 0xffffffff
is an expected invalid bit pattern that should be checked before BT_Active and
BT_State are masked with 0x00ffffff, so for now, this fix seems like the least
risky approach.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c b/drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c
index bfcbd7a..6989580 100644
--- a/drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c
+++ b/drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c
@@ -9824,7 +9824,7 @@ void BTDM_CheckBTIdleChange1Ant(struct rtw_adapter *padapter)
 	BT_Polling = rtl8723au_read32(padapter, regBTPolling);
 	RTPRINT(FBT, BT_TRACE, ("[DM][BT], BT_Polling(0x%x) =%x\n", regBTPolling, BT_Polling));
 
-	if (BT_Active == 0xffffffff && BT_State == 0xffffffff && BT_Polling == 0xffffffff)
+	if (BT_Active == 0x00ffffff && BT_State == 0x00ffffff && BT_Polling == 0xffffffff)
 		return;
 	if (BT_Polling == 0)
 		return;
-- 
2.8.1

Re: [PATCH] staging: rtl8723au: hal: check BT_Active and BT_State with correct bit pattern

[Jes Sorensen]

Colin King <colin.king@canonical.com> writes:
> From: Colin Ian King <colin.king@canonical.com>
>
> BT_Active and BT_State are being masked with 0x00ffffff so it the subsequent
> comparisons with 0xffffffff are therefore a buggy check.  Instead, check them
> against 0x00ffffff.
>
> Unfortunately I couldn't find a datasheet or hardware to see if 0xffffffff
> is an expected invalid bit pattern that should be checked before BT_Active and
> BT_State are masked with 0x00ffffff, so for now, this fix seems like the least
> risky approach.
>
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

I don't really know about the BT parts here, since I never did anything
with that part of the chip. Larry probably knows more.

The only question is whether fixing this bug changes behavior that has
unexpected side effects?

Cheers,
Jes

>
> diff --git a/drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c b/drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c
> index bfcbd7a..6989580 100644
> --- a/drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c
> +++ b/drivers/staging/rtl8723au/hal/rtl8723a_bt-coexist.c
> @@ -9824,7 +9824,7 @@ void BTDM_CheckBTIdleChange1Ant(struct rtw_adapter *padapter)
>  	BT_Polling = rtl8723au_read32(padapter, regBTPolling);
>  	RTPRINT(FBT, BT_TRACE, ("[DM][BT], BT_Polling(0x%x) =%x\n", regBTPolling, BT_Polling));
>  
> -	if (BT_Active == 0xffffffff && BT_State == 0xffffffff && BT_Polling == 0xffffffff)
> +	if (BT_Active == 0x00ffffff && BT_State == 0x00ffffff && BT_Polling == 0xffffffff)
>  		return;
>  	if (BT_Polling == 0)
>  		return;