[PATCH net] mvpp2: enable rxhash only on the first port

[PATCH net] mvpp2: enable rxhash only on the first port

[Matteo Croce]

Currently rxhash only works on the first port of the CP (Communication
Processor). Enabling it on other ports completely blocks packet reception.
This patch only adds rxhash as supported feature to the first port,
so rxhash can't be enabled on other ports:

	# ethtool -K eth0 rxhash on
	# ethtool -K eth1 rxhash on
	# ethtool -K eth2 rxhash on
	Cannot change receive-hashing
	Could not change any device features
	# ethtool -K eth3 rxhash on
	Cannot change receive-hashing
	Could not change any device features

Fixes: 895586d5dc32 ("net: mvpp2: cls: Use RSS contexts to handle RSS tables")
Signed-off-by: Matteo Croce <mcroce@redhat.com>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index 2b5dad2ec650..ba71583c7ae3 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -5423,7 +5423,8 @@ static int mvpp2_port_probe(struct platform_device *pdev,
 			    NETIF_F_HW_VLAN_CTAG_FILTER;
 
 	if (mvpp22_rss_is_supported()) {
-		dev->hw_features |= NETIF_F_RXHASH;
+		if (port->id == 0)
+			dev->hw_features |= NETIF_F_RXHASH;
 		dev->features |= NETIF_F_NTUPLE;
 	}
 
-- 
2.26.2

Re: [PATCH net] mvpp2: enable rxhash only on the first port

[Russell King - ARM Linux admin]

On Sat, May 09, 2020 at 04:15:46PM +0200, Matteo Croce wrote:
> Currently rxhash only works on the first port of the CP (Communication
> Processor). Enabling it on other ports completely blocks packet reception.
> This patch only adds rxhash as supported feature to the first port,
> so rxhash can't be enabled on other ports:
> 
> 	# ethtool -K eth0 rxhash on
> 	# ethtool -K eth1 rxhash on
> 	# ethtool -K eth2 rxhash on
> 	Cannot change receive-hashing
> 	Could not change any device features
> 	# ethtool -K eth3 rxhash on
> 	Cannot change receive-hashing
> 	Could not change any device features
> 
> Fixes: 895586d5dc32 ("net: mvpp2: cls: Use RSS contexts to handle RSS tables")
> Signed-off-by: Matteo Croce <mcroce@redhat.com>
> ---
>  drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> index 2b5dad2ec650..ba71583c7ae3 100644
> --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> @@ -5423,7 +5423,8 @@ static int mvpp2_port_probe(struct platform_device *pdev,
>  			    NETIF_F_HW_VLAN_CTAG_FILTER;
>  
>  	if (mvpp22_rss_is_supported()) {
> -		dev->hw_features |= NETIF_F_RXHASH;
> +		if (port->id == 0)
> +			dev->hw_features |= NETIF_F_RXHASH;
>  		dev->features |= NETIF_F_NTUPLE;
>  	}

I seem to have discovered the cause of the problem in the old thread,
so I suggest we wait and see whether anyone offers up a proper
solution to this regression before we rush to completely disable
this feature.

I would suggest with a high degress of confidence based on my
research that prior to the offending commit (895586d5dc32), rx
hashing was working fine, distributing interrupts across the cores.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 10.2Mbps down 587kbps up

Re: [PATCH net] mvpp2: enable rxhash only on the first port

[Jakub Kicinski]

On Sat, 9 May 2020 21:23:55 +0100 Russell King - ARM Linux admin wrote:
> I seem to have discovered the cause of the problem in the old thread,
> so I suggest we wait and see whether anyone offers up a proper
> solution to this regression before we rush to completely disable
> this feature.
> 
> I would suggest with a high degress of confidence based on my
> research that prior to the offending commit (895586d5dc32), rx
> hashing was working fine, distributing interrupts across the cores.

Ack, dropping this from patchwork for now. Thanks for the guidance.