netdev - Re: [PATCH] ftgmac100: Disable HW checksum generation on AST2500

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Message-ID: <8A8392C8-5E5E-444D-AB1B-E0FAD3C29425@fb.com>
Date:   Wed, 11 Sep 2019 18:30:38 +0000
From:   Vijay Khemka <vijaykhemka@...com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        YueHaibing <yuehaibing@...wei.com>, Andrew Lunn <andrew@...n.ch>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        "Mauro Carvalho Chehab" <mchehab+samsung@...nel.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "openbmc @ lists . ozlabs . org" <openbmc@...ts.ozlabs.org>,
        Sai Dasari <sdasari@...com>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>
Subject: Re: [PATCH] ftgmac100: Disable HW checksum generation on AST2500



On 9/10/19, 4:08 PM, "Linux-aspeed on behalf of Vijay Khemka" <linux-aspeed-bounces+vijaykhemka=fb.com@...ts.ozlabs.org on behalf of vijaykhemka@...com> wrote:

    
    
    On 9/10/19, 3:50 PM, "Linux-aspeed on behalf of Vijay Khemka" <linux-aspeed-bounces+vijaykhemka=fb.com@...ts.ozlabs.org on behalf of vijaykhemka@...com> wrote:
    
        
        
        On 9/10/19, 3:05 PM, "Florian Fainelli" <f.fainelli@...il.com> wrote:
        
            On 9/10/19 2:37 PM, Vijay Khemka wrote:
            > HW checksum generation is not working for AST2500, specially with IPV6
            > over NCSI. All TCP packets with IPv6 get dropped. By disabling this
            > it works perfectly fine with IPV6.
            > 
            > Verified with IPV6 enabled and can do ssh.
            
            How about IPv4, do these packets have problem? If not, can you continue
            advertising NETIF_F_IP_CSUM but take out NETIF_F_IPV6_CSUM?
        
        I changed code from (netdev->hw_features &= ~NETIF_F_HW_CSUM) to 
        (netdev->hw_features &= ~NETIF_F_ IPV6_CSUM). And it is not working. 
        Don't know why. IPV4 works without any change but IPv6 needs HW_CSUM
        Disabled.
    
    Now I changed to
    netdev->hw_features &= (~NETIF_F_HW_CSUM) | NETIF_F_IP_CSUM;
    And it works.

I investigated more on these features and found that we cannot set NETIF_F_IP_CSUM 
While NETIF_F_HW_CSUM is set. So I disabled NETIF_F_HW_CSUM first and enabled
NETIF_F_IP_CSUM in next statement. And it works fine.

But as per line 166 in include/linux/skbuff.h,  
*   NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM are being deprecated in favor of
 *   NETIF_F_HW_CSUM. New devices should use NETIF_F_HW_CSUM to indicate
 *   checksum offload capability.

Please suggest which of below 2 I should do. As both works for me.
1. Disable completely NETIF_F_HW_CSUM and do nothing. This is original patch.
2. Enable NETIF_F_IP_CSUM in addition to 1. I can have v2 if this is accepted.
            
            > 
            > Signed-off-by: Vijay Khemka <vijaykhemka@...com>
            > ---
            >  drivers/net/ethernet/faraday/ftgmac100.c | 5 +++--
            >  1 file changed, 3 insertions(+), 2 deletions(-)
            > 
            > diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
            > index 030fed65393e..591c9725002b 100644
            > --- a/drivers/net/ethernet/faraday/ftgmac100.c
            > +++ b/drivers/net/ethernet/faraday/ftgmac100.c
            > @@ -1839,8 +1839,9 @@ static int ftgmac100_probe(struct platform_device *pdev)
            >  	if (priv->use_ncsi)
            >  		netdev->hw_features |= NETIF_F_HW_VLAN_CTAG_FILTER;
            >  
            > -	/* AST2400  doesn't have working HW checksum generation */
            > -	if (np && (of_device_is_compatible(np, "aspeed,ast2400-mac")))
            > +	/* AST2400  and AST2500 doesn't have working HW checksum generation */
            > +	if (np && (of_device_is_compatible(np, "aspeed,ast2400-mac") ||
            > +		   of_device_is_compatible(np, "aspeed,ast2500-mac")))
            >  		netdev->hw_features &= ~NETIF_F_HW_CSUM;
            >  	if (np && of_get_property(np, "no-hw-checksum", NULL))
            >  		netdev->hw_features &= ~(NETIF_F_HW_CSUM | NETIF_F_RXCSUM);
            > 
            
            
            -- 
            Florian