netdev - RE: [PATCH net v2] net: renesas: rswitch: Fix timestamp feature after all descriptors are used

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Message-ID:
 <TYBPR01MB53412B2656A2B4756258042BD850A@TYBPR01MB5341.jpnprd01.prod.outlook.com>
Date: Thu, 8 Jun 2023 00:57:37 +0000
From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To: Hao Lan <lanhao@...wei.com>, "s.shtylyov@....ru" <s.shtylyov@....ru>,
	"davem@...emloft.net" <davem@...emloft.net>, "edumazet@...gle.com"
	<edumazet@...gle.com>, "kuba@...nel.org" <kuba@...nel.org>,
	"pabeni@...hat.com" <pabeni@...hat.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	Phong Hoang <phong.hoang.wz@...esas.com>
Subject: RE: [PATCH net v2] net: renesas: rswitch: Fix timestamp feature after
 all descriptors are used

Hi again,

> From: Yoshihiro Shimoda, Sent: Thursday, June 8, 2023 9:21 AM
> 
> Hi Hao,
> 
> > From: Hao Lan, Sent: Wednesday, June 7, 2023 8:28 PM
> >
> > On 2023/6/7 15:01, Yoshihiro Shimoda wrote:
> > > diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> > > index aace87139cea..049adbf5a642 100644
> > > --- a/drivers/net/ethernet/renesas/rswitch.c
> > > +++ b/drivers/net/ethernet/renesas/rswitch.c
> > > @@ -420,7 +420,7 @@ static int rswitch_gwca_queue_format(struct net_device *ndev,
> > >  }
> > >
> > >  static void rswitch_gwca_ts_queue_fill(struct rswitch_private *priv,
> > > -				       int start_index, int num)
> > > +				       int start_index, int num, bool last)
> > >  {
> > >  	struct rswitch_gwca_queue *gq = &priv->gwca.ts_queue;
> > >  	struct rswitch_ts_desc *desc;
> > > @@ -431,6 +431,12 @@ static void rswitch_gwca_ts_queue_fill(struct rswitch_private *priv,
> > >  		desc = &gq->ts_ring[index];
> > >  		desc->desc.die_dt = DT_FEMPTY_ND | DIE;
> > >  	}
> > > +
> > > +	if (last) {
> > > +		desc = &gq->ts_ring[gq->ring_size];
> > > +		rswitch_desc_set_dptr(&desc->desc, gq->ring_dma);
> > > +		desc->desc.die_dt = DT_LINKFIX;
> > > +	}
> > >  }
> > >
> > Hello Yoshihiro Shimoda，
> >
> > Does your function set the last descriptor to hardware on initialization, but not at other times?
> 
> The last descriptor initialization is needed at the first time. So, after the initialization,
> the last setting will not run anymore.
> 
> > I think rswitch_gwca_ts_queue_fill should be implemented in a separate function,
> > not use the 'last' distinguish the last descriptor.
> 
> I got it. I'll modify this patch on v3.
> 
> > But if it should be setting every cycle, I think rswitch_gwca_queue_ext_ts_fill should
> > check if the descriptor is the last in the queue and set the LINKFIX flag.
> 
> Thank you for the comment. The last descriptor should not be setting every cycle.
> To implement the code for consistency, I think that I should add rswitch_tsdesc_init()
> rswitch_gwca_queue_format() like rswitch_txdmac_init() and rswitch_gwca_queue_format()

About ts_queue, it is similar with linkfix, not txdmac. So, now I'm thinking that modifying
the rswitch_gwca_ts_queue_alloc() is suitable.

Best regards,
Yoshihiro Shimoda

> Best regards,
> Yoshihiro Shimoda
> 
> > >  static int rswitch_gwca_queue_ext_ts_fill(struct net_device *ndev,
> > > @@ -941,7 +947,7 @@ static void rswitch_ts(struct rswitch_private *priv)
> > >  	}
> > >
> > >  	num = rswitch_get_num_cur_queues(gq);
> > > -	rswitch_gwca_ts_queue_fill(priv, gq->dirty, num);
> > > +	rswitch_gwca_ts_queue_fill(priv, gq->dirty, num, false);
> > >  	gq->dirty = rswitch_next_queue_index(gq, false, num);
> > >  }
> > >
> > > @@ -1780,7 +1786,7 @@ static int rswitch_init(struct rswitch_private *priv)
> > >  	if (err < 0)
> > >  		goto err_ts_queue_alloc;
> > >
> > > -	rswitch_gwca_ts_queue_fill(priv, 0, TS_RING_SIZE);
> > > +	rswitch_gwca_ts_queue_fill(priv, 0, TS_RING_SIZE, true);
> > >  	INIT_LIST_HEAD(&priv->gwca.ts_info_list);
> > >
> > >  	for (i = 0; i < RSWITCH_NUM_PORTS; i++) {
> > >