Message-ID: <45F78498.8080608@lwfinger.net>
Date: Wed, 14 Mar 2007 00:14:00 -0500
From: Larry Finger <larry.finger@lwfinger.net>
MIME-Version: 1.0
To: Stefano Brivio <stefano.brivio@polimi.it>
CC: bcm43xx-dev@lists.berlios.de, linux-wireless@vger.kernel.org
Subject: Re: [RFT] [PATCH] bcm43xx: ACI fixes
References: <20070312010420.353a59c0@localhost>
In-Reply-To: <20070312010420.353a59c0@localhost>
Content-Type: text/plain; charset=US-ASCII
Sender: linux-wireless-owner@vger.kernel.org

Stefano,

As noted earlier on the list, I have started testing this patch. In setting the various interference
modes, I have found some bugs in other places that were not previously tested. Thanks for this
contribution.

I have some comments below.

Stefano Brivio wrote:
> Please test the following patch. It syncs ACI (Adjacent Channels
> Interference) code to specs. I can't test it right now. Will port to
> mac80211 branch ASAP.
> 
> 
> Signed-off-by: Stefano Brivio <stefano.brivio@polimi.it>
> ----
> 
> diff --git a/drivers/net/wireless/bcm43xx/bcm43xx.h b/drivers/net/wireless/bcm43xx/bcm43xx.h
> index 95ff175..7023327 100644
> --- a/drivers/net/wireless/bcm43xx/bcm43xx.h
> +++ b/drivers/net/wireless/bcm43xx/bcm43xx.h
> @@ -398,6 +398,9 @@
>  #define BCM43xx_DEFAULT_SHORT_RETRY_LIMIT	7
>  #define BCM43xx_DEFAULT_LONG_RETRY_LIMIT	4
>  
> +/* Statscounter offsets. */
> +#define BCM43xx_SC_ACI		0x2E
> +
>  /* FIXME: the next line is a guess as to what the maximum RSSI value might be */
>  #define RX_RSSI_MAX				60
>  
> @@ -550,7 +553,11 @@ struct bcm43xx_phyinfo {
>  	u8 connected:1,
>  	   calibrated:1,
>  	   is_locked:1, /* used in bcm43xx_phy_{un}lock() */
> -	   dyn_tssi_tbl:1; /* used in bcm43xx_phy_init_tssi2dbm_table() */
> +	   dyn_tssi_tbl:1, /* used in bcm43xx_phy_init_tssi2dbm_table() */
> +	   g_interfmode:1; /* bit 4000 in PHY_G_CRS, used in periodic tasks */
> +	u8 g_interfmode_timer; /* how much time ago g_interfmode was unset */
> +	u16 g_sc_saved; /* used in periodic tasks for ACI */
> +
>  	/* LO Measurement Data.
>  	 * Use bcm43xx_get_lopair() to get a value.
>  	 */
> @@ -629,7 +636,9 @@ struct bcm43xx_radioinfo {
>  	/* ACI (adjacent channel interference) flags. */
>  	u8 aci_enable:1,
>  	   aci_wlan_automatic:1,
> -	   aci_hw_rssi:1;
> +	   aci_hw_rssi:1,
> +	   aci_delay:5;
Should this be a bit field? Why not just make it a u8?
> +	u8 aci_start;
>  };
>  
>  /* Data structures for DMA transmission, per 80211 core. */
> @@ -699,6 +708,18 @@ struct bcm43xx_noise_calculation {
>  	s8 samples[8][4];
>  };
>  
> +/* Statscounter data (currently ACI only). */
> +struct bcm43xx_statscounter_saved {
> +	u16 aci;
> +};
> +
> +/* Values for ACI moving average calculation. */
> +struct bcm43xx_aci_saved {
> +	u16 value[8];
> +	u8 next:3,
> +	   set:3;
As I will explain later, I don't think 'set' is needed. I also recommend having 'next' be a plain u8.
> +};
> +
>  struct bcm43xx_stats {
>  	u8 noise;
>  	struct iw_statistics wstats;
> @@ -812,6 +833,10 @@ struct bcm43xx_private {
>  	u32 irq_savedstate;
>  	/* Link Quality calculation context. */
>  	struct bcm43xx_noise_calculation noisecalc;
> +	/* Statscounter tracking. */
> +	struct bcm43xx_statscounter_saved sc;
> +	/* ACI tracking. */
> +	struct bcm43xx_aci_saved aci;
>  	/* if > 0 MAC is suspended. if == 0 MAC is enabled. */
>  	int mac_suspended;
>  
> diff --git a/drivers/net/wireless/bcm43xx/bcm43xx_main.c b/drivers/net/wireless/bcm43xx/bcm43xx_main.c
> index e594af4..27ec519 100644
> --- a/drivers/net/wireless/bcm43xx/bcm43xx_main.c
> +++ b/drivers/net/wireless/bcm43xx/bcm43xx_main.c
> @@ -3059,6 +3059,44 @@ static void bcm43xx_pcie_mdio_write(stru
>  	bcm43xx_write32(bcm, BCM43xx_PCIECORE_MDIO_CTL, 0);
>  }
>  
> +/* We don't use any statscounter other than ACI for now */
> +static u16 bcm43xx_sc_read(struct bcm43xx_private *bcm)
> +{
> +	struct bcm43xx_statscounter_saved *sc = &bcm->sc;
> +	u16 tmp;
> +
> +	tmp = bcm43xx_shm_read16(bcm, BCM43xx_SHM_SHARED, 0x80 + BCM43xx_SC_ACI)
> +		- sc->aci;
> +	if (tmp)
> +		sc->aci += tmp;
> +
> +	return tmp;
> +}
> +
> +static u16 bcm43xx_aci_moving_average(struct bcm43xx_private *bcm)
> +{
> +	struct bcm43xx_aci_saved *aci = &bcm->aci;
> +
> +	u8 i;
> +	u16 avg;
> +	u32 sum = 0;
> +
> +	aci->value[aci->next] = bcm43xx_sc_read(bcm);
> +	if (unlikely(aci->set < 7))
> +		aci->set++;
I don't think the variable aci->set is needed as the divisor is alway 8 in the calculation of the
average below. Any error in the average shouldn't be important as it will occur only in the first
cycle through the value buffer. The for loop below should end at i < 8. There will be extra
calculations only during the first buffer cycle.
> +	for (i = 0; i < aci->set; i++)
> +		sum += aci->value[i];
> +	avg = sum / (u16)8;
Why the cast here? I didn't get any gcc warnings without it. I expect this ends up as a shift right
anyway.
> +	if ((sum % 8) > 3)
> +		avg++;
> +	if (aci->next < 7)
> +		aci->next++;
> +	else
> +		aci->next = 0;
Why not auto-increment aci->next in the line where bcm43xx_sc_read is called. Then you only need to
test for next > 7 and reset it to zero then.
> +
> +	return avg;
> +}

Larry