linux-kernel - Re: [PATCH net v2 2/2] net: dsa: b53: Support setting learning on port

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Date:   Mon, 22 Feb 2021 15:44:21 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     netdev@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net v2 2/2] net: dsa: b53: Support setting learning on
 port



On 2/22/2021 3:18 PM, Vladimir Oltean wrote:
> On Mon, Feb 22, 2021 at 02:30:10PM -0800, Florian Fainelli wrote:
>> diff --git a/drivers/net/dsa/b53/b53_regs.h b/drivers/net/dsa/b53/b53_regs.h
>> index c90985c294a2..b2c539a42154 100644
>> --- a/drivers/net/dsa/b53/b53_regs.h
>> +++ b/drivers/net/dsa/b53/b53_regs.h
>> @@ -115,6 +115,7 @@
>>  #define B53_UC_FLOOD_MASK		0x32
>>  #define B53_MC_FLOOD_MASK		0x34
>>  #define B53_IPMC_FLOOD_MASK		0x36
>> +#define B53_DIS_LEARNING		0x3c
>>  
>>  /*
>>   * Override Ports 0-7 State on devices with xMII interfaces (8 bit)
>> diff --git a/drivers/net/dsa/bcm_sf2.c b/drivers/net/dsa/bcm_sf2.c
>> index 3eaedbb12815..5ee8103b8e9c 100644
>> --- a/drivers/net/dsa/bcm_sf2.c
>> +++ b/drivers/net/dsa/bcm_sf2.c
>> @@ -223,23 +223,10 @@ static int bcm_sf2_port_setup(struct dsa_switch *ds, int port,
>>  	reg &= ~P_TXQ_PSM_VDD(port);
>>  	core_writel(priv, reg, CORE_MEM_PSM_VDD_CTRL);
>>  
>> -	/* Enable learning */
>> -	reg = core_readl(priv, CORE_DIS_LEARN);
>> -	reg &= ~BIT(port);
>> -	core_writel(priv, reg, CORE_DIS_LEARN);
>> -
>>  	/* Enable Broadcom tags for that port if requested */
>> -	if (priv->brcm_tag_mask & BIT(port)) {
>> +	if (priv->brcm_tag_mask & BIT(port))
>>  		b53_brcm_hdr_setup(ds, port);
>>  
>> -		/* Disable learning on ASP port */
>> -		if (port == 7) {
>> -			reg = core_readl(priv, CORE_DIS_LEARN);
>> -			reg |= BIT(port);
>> -			core_writel(priv, reg, CORE_DIS_LEARN);
>> -		}
>> -	}
>> -
> 
> In sf2, CORE_DIS_LEARN is at address 0xf0, while in b53, B53_DIS_LEARN
> is at 0x3c. Are they even configuring the same thing?

They are the SF2 switch was integrated with a bridge that would flatten
its address space such that there would be no need to access the
registers indirectly like what b53_srab does.

This is the reason why we have the SF2_PAGE_REG_MKADDR() macro to
convert from a {page, offset} tuple to a memory mapped address and here
0x3c << 2 = 0xf0.
-- 
Florian