Re: [Intel-wired-lan] [PATCH iwl-next v2 1/3] igb: prepare for RSS key get/set support

[Takashi Kozu <takkozu@amazon.com>]

> From: Paul Menzel <pmenzel@molgen.mpg.de>
> To: Takashi Kozu <takkozu@amazon.com>
> Cc: anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com,
> andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com,
> kuba@kernel.org, pabeni@redhat.com,
> intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
> Kohei Enju <enjuk@amazon.com>
> Subject: Re: [Intel-wired-lan] [PATCH iwl-next v2 1/3] igb: prepare for RSS key get/set support
> Date: Thu, 8 Jan 2026 13:27:57 +0100 [thread overview]
> Message-ID: <2ad8d26a-794c-498b-a09b-5791acb0a9d5@molgen.mpg.de> (raw)
> In-Reply-To: <20260108052020.84218-6-takkozu@amazon.com>
> 
> Dear Takashi,
> 
> 
> Thank you for the patch.
> 
> Am 08.01.26 um 06:20 schrieb Takashi Kozu:
> > Store the RSS key inside struct igb_adapter and introduce the
> > igb_write_rss_key() helper function. This allows the driver to program
> > the E1000 registers using a persistent RSS key, instead of using a
> > stack-local buffer in igb_setup_mrqc().
> >
> > Tested-by: Kohei Enju <enjuk@amazon.com>
> > Signed-off-by: Takashi Kozu <takkozu@amazon.com>
> > ---
> > drivers/net/ethernet/intel/igb/igb.h | 3 +++
> > drivers/net/ethernet/intel/igb/igb_ethtool.c | 12 ++++++++++++
> > drivers/net/ethernet/intel/igb/igb_main.c | 6 ++----
> > 3 files changed, 17 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
> > index 0fff1df81b7b..8c9b02058cec 100644
> > --- a/drivers/net/ethernet/intel/igb/igb.h
> > +++ b/drivers/net/ethernet/intel/igb/igb.h
> > @@ -495,6 +495,7 @@ struct hwmon_buff {
> > #define IGB_N_PEROUT 2
> > #define IGB_N_SDP 4
> > #define IGB_RETA_SIZE 128
> > +#define IGB_RSS_KEY_SIZE 40
> >
> > enum igb_filter_match_flags {
> > IGB_FILTER_FLAG_ETHER_TYPE = 0x1,
> > @@ -655,6 +656,7 @@ struct igb_adapter {
> > struct i2c_client *i2c_client;
> > u32 rss_indir_tbl_init;
> > u8 rss_indir_tbl[IGB_RETA_SIZE];
> > + u8 rss_key[IGB_RSS_KEY_SIZE];
> >
> > unsigned long link_check_timeout;
> > int copper_tries;
> > @@ -735,6 +737,7 @@ void igb_down(struct igb_adapter *);
> > void igb_reinit_locked(struct igb_adapter *);
> > void igb_reset(struct igb_adapter *);
> > int igb_reinit_queues(struct igb_adapter *);
> > +void igb_write_rss_key(struct igb_adapter *adapter);
> > void igb_write_rss_indir_tbl(struct igb_adapter *);
> > int igb_set_spd_dplx(struct igb_adapter *, u32, u8);
> > int igb_setup_tx_resources(struct igb_ring *);
> > diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c
> > index 10e2445e0ded..8695ff28a7b8 100644
> > --- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
> > +++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
> > @@ -3016,6 +3016,18 @@ static int igb_set_rxnfc(struct net_device *dev, struct ethtool_rxnfc *cmd)
> > return ret;
> > }
> >
> > +void igb_write_rss_key(struct igb_adapter *adapter)
> > +{
> > + struct e1000_hw *hw = &adapter->hw;
> > + u32 val;
> > + int i;
> > +
> > + for (i = 0; i < IGB_RSS_KEY_SIZE / 4; i++) {
> > + val = get_unaligned_le32(&adapter->rss_key[i info.plist 4]);
> 
> Why is `get_unaligned_le32()` needed?

I think it's necessary in order to align to 4 bytes.