Subject: Re: [PATCH v5 net-next 2/2] net: airoha: Introduce ethernet support for EN7581 SoC

From: Simon Horman <[email-masked]>
Date: Sat, 6 Jul 2024 13:27:54 +0100

On Sat, Jul 06, 2024 at 10:27:00AM +0200, Lorenzo Bianconi wrote:
> > On Thu, Jul 04, 2024 at 10:08:11AM +0200, Lorenzo Bianconi wrote:
> > > Add airoha_eth driver in order to introduce ethernet support for
> > > Airoha EN7581 SoC available on EN7581 development board (en7581-evb).
> > > en7581-evb networking architecture is composed by airoha_eth as mac
> > > controller (cpu port) and a mt7530 dsa based switch.
> > > EN7581 mac controller is mainly composed by Frame Engine (FE) and
> > > QoS-DMA (QDMA) modules. FE is used for traffic offloading (just basic
> > > functionalities are supported now) while QDMA is used for DMA operation
> > > and QOS functionalities between mac layer and the dsa switch (hw QoS is
> > > not available yet and it will be added in the future).
> > > Currently only hw lan features are available, hw wan will be added with
> > > subsequent patches.
> > > 
> > > Tested-by: Benjamin Larsson <[email-masked]>
> > > Signed-off-by: Lorenzo Bianconi <[email-masked]>
> > 
> > ...
> > 
> > > +static const char * const airoha_ethtool_stats_name[] = {
> > > +	"tx_eth_pkt_cnt",
> > > +	"tx_eth_byte_cnt",
> > > +	"tx_ok_pkt_cnt",
> > > +	"tx_ok_byte_cnt",
> > > +	"tx_eth_drop_cnt",
> > > +	"tx_eth_bc_cnt",
> > > +	"tx_eth_mc_cnt",
> > > +	"tx_eth_lt64_cnt",
> > > +	"tx_eth_eq64_cnt",
> > > +	"tx_eth_65_127_cnt",
> > > +	"tx_eth_128_255_cnt",
> > > +	"tx_eth_256_511_cnt",
> > > +	"tx_eth_512_1023_cnt",
> > > +	"tx_eth_1024_1518_cnt",
> > > +	"tx_eth_gt1518_cnt",
> > > +	"rx_eth_pkt_cnt",
> > > +	"rx_eth_byte_cnt",
> > > +	"rx_ok_pkt_cnt",
> > > +	"rx_ok_byte_cnt",
> > > +	"rx_eth_drop_cnt",
> > > +	"rx_eth_bc_cnt",
> > > +	"rx_eth_mc_cnt",
> > > +	"rx_eth_crc_drop_cnt",
> > > +	"rx_eth_frag_cnt",
> > > +	"rx_eth_jabber_cnt",
> > > +	"rx_eth_lt64_cnt",
> > > +	"rx_eth_eq64_cnt",
> > > +	"rx_eth_65_127_cnt",
> > > +	"rx_eth_128_255_cnt",
> > > +	"rx_eth_256_511_cnt",
> > > +	"rx_eth_512_1023_cnt",
> > > +	"rx_eth_1024_1518_cnt",
> > > +	"rx_eth_gt1518_cnt",
> > > +};
> > 
> > Hi Lorenzo,
> > 
> > Sorry for not noticing this earlier.
> 
> Hi Simon,
> 
> no worries :)
> 
> > It seems to me that some of the stats above could
> > use standard stats, which is preferred.
> 
> Please correct me if I am wrong but it seems quite a common approach to have
> same stats in both .ndo_get_stats64() and .get_ethtool_stats():
> - https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/mediatek/mtk_eth_soc.c#L212
> - https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/marvell/mvneta.c#L435
> - https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/intel/i40e/i40e_ethtool.c#L243
> - https://github.com/torvalds/linux/blob/master/net/mac80211/ethtool.c#L52
> - ...
> 
> Do you mean I should just report common stats (e.g. tx_packets or tx_bytes) in
> .ndo_get_stats64()? Or it is fine to just add .ndo_get_stats64() callback (not
> supported at the moment)?

The first option: It is my understanding that it preferred to only
report common stats via ndo_get_stats64.

  "Please limit stats you report in ethtool -S to just the stats for which
   proper interfaces don't exist. Don't duplicate what's already reported
   via rtase_get_stats64(), also take a look at what can be reported via
   various *_stats members of struct ethtool_ops."

   - Re: [PATCH net-next v18 10/13] rtase: Implement ethtool function
     by Jakub Kicinski
     https://lore.kernel.org/netdev/[email-masked]/

> > Basically, my understanding is that one should:
> > 1. Implement .ndo_get_stats64
> >    (that seems relevant here)
> > 2. As appropriate implement ethtool_stats non-extended stats operations
> >    (perhaps not relevant here)
> 
> Can you please provide me a pointer for it?

Sorry, that was not at all clear.
I meant, as per the quote above, *_stats members of struct ethtool_ops,
other than those that implement extended ops.
e.g. get_rmon_stats.

> 
> Regards,
> Lorenzo
> 
> > 3. Then implement get_ethtool_stats for what is left over
> > 
> > ...