Re: [PATCH net] net: systemport: set dev->max_mtu to UMAC_MAX_MTU_SIZE

[Florian Fainelli <f.fainelli@gmail.com>]

On 12/18/20 12:24 PM, Vladimir Oltean wrote:
> Hi Florian,
> 
> On Fri, Dec 18, 2020 at 09:38:43AM -0800, Florian Fainelli wrote:
>> The driver is already allocating receive buffers of 2KiB and the
>> Ethernet MAC is configured to accept frames up to UMAC_MAX_MTU_SIZE.
>>
>> Fixes: bfcb813203e6 ("net: dsa: configure the MTU for switch ports")
>> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
>> ---
>>  drivers/net/ethernet/broadcom/bcmsysport.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c
>> index 0fdd19d99d99..b1ae9eb8f247 100644
>> --- a/drivers/net/ethernet/broadcom/bcmsysport.c
>> +++ b/drivers/net/ethernet/broadcom/bcmsysport.c
>> @@ -2577,6 +2577,7 @@ static int bcm_sysport_probe(struct platform_device *pdev)
>>  			 NETIF_F_HW_VLAN_CTAG_TX;
>>  	dev->hw_features |= dev->features;
>>  	dev->vlan_features |= dev->features;
>> +	dev->max_mtu = UMAC_MAX_MTU_SIZE;
>>  
>>  	/* Request the WOL interrupt and advertise suspend if available */
>>  	priv->wol_irq_disabled = 1;
>> -- 
>> 2.25.1
>>
> 
> Do you want to treat the SYSTEMPORT Lite differently?
> 
> 	/* Set maximum frame length */
> 	if (!priv->is_lite)
> 		umac_writel(priv, UMAC_MAX_MTU_SIZE, UMAC_MAX_FRAME_LEN);
> 	else
> 		gib_set_pad_extension(priv);

SYSTEMPORT Lite does not actually validate the frame length, so setting
a maximum number to the buffer size we allocate could work, but I don't
see a reason to differentiate the two types of MACs here.
-- 
Florian