[PATCH v5 net-next 02/14] net: enetc: add command BD ring support for i.MX95 ENETC

[Wei Fang]

> -----Original Message-----
> From: Vladimir Oltean <olteanv at gmail.com>
> Sent: 2025年4月18日 21:25
> To: Wei Fang <wei.fang at nxp.com>
> Cc: Claudiu Manoil <claudiu.manoil at nxp.com>; Vladimir Oltean
> <vladimir.oltean at nxp.com>; Clark Wang <xiaoning.wang at nxp.com>;
> andrew+netdev at lunn.ch; davem at davemloft.net; edumazet at google.com;
> kuba at kernel.org; pabeni at redhat.com; christophe.leroy at csgroup.eu;
> netdev at vger.kernel.org; linux-kernel at vger.kernel.org; imx at lists.linux.dev;
> linuxppc-dev at lists.ozlabs.org; linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH v5 net-next 02/14] net: enetc: add command BD ring
> support for i.MX95 ENETC
> 
> On Fri, Apr 11, 2025 at 05:57:40PM +0800, Wei Fang wrote:
> > diff --git a/drivers/net/ethernet/freescale/enetc/enetc_cbdr.c
> b/drivers/net/ethernet/freescale/enetc/enetc_cbdr.c
> > index 20bfdf7fb4b4..ecb571e5ea50 100644
> > --- a/drivers/net/ethernet/freescale/enetc/enetc_cbdr.c
> > +++ b/drivers/net/ethernet/freescale/enetc/enetc_cbdr.c
> > @@ -60,6 +60,45 @@ void enetc_teardown_cbdr(struct enetc_cbdr *cbdr)
> >  }
> >  EXPORT_SYMBOL_GPL(enetc_teardown_cbdr);
> >
> > +int enetc4_setup_cbdr(struct enetc_si *si)
> > +{
> > +	struct ntmp_user *user = &si->ntmp_user;
> > +	struct device *dev = &si->pdev->dev;
> > +	struct enetc_hw *hw = &si->hw;
> > +	struct netc_cbdr_regs regs;
> > +
> > +	user->cbdr_num = 1;
> > +	user->cbdr_size = NETC_CBDR_BD_NUM;
> > +	user->dev = dev;
> > +	user->ring = devm_kcalloc(dev, user->cbdr_num,
> > +				  sizeof(struct netc_cbdr), GFP_KERNEL);
> > +	if (!user->ring)
> > +		return -ENOMEM;
> > +
> > +	/* set CBDR cache attributes */
> > +	enetc_wr(hw, ENETC_SICAR2,
> > +		 ENETC_SICAR_RD_COHERENT | ENETC_SICAR_WR_COHERENT);
> > +
> > +	regs.pir = hw->reg + ENETC_SICBDRPIR;
> > +	regs.cir = hw->reg + ENETC_SICBDRCIR;
> > +	regs.mr = hw->reg + ENETC_SICBDRMR;
> > +	regs.bar0 = hw->reg + ENETC_SICBDRBAR0;
> > +	regs.bar1 = hw->reg + ENETC_SICBDRBAR1;
> > +	regs.lenr = hw->reg + ENETC_SICBDRLENR;
> > +
> > +	return netc_setup_cbdr(dev, user->cbdr_size, &regs, user->ring);
> > +}
> > +EXPORT_SYMBOL_GPL(enetc4_setup_cbdr);
> > +
> > +void enetc4_teardown_cbdr(struct enetc_si *si)
> > +{
> > +	struct ntmp_user *user = &si->ntmp_user;
> > +
> > +	netc_teardown_cbdr(user->dev, user->ring);
> > +	user->dev = NULL;
> > +}
> > +EXPORT_SYMBOL_GPL(enetc4_teardown_cbdr);
> 
> I wanted to ask why isn't netc_setup_cbdr() merged into enetc4_setup_cbdr()
> (and likewise for teardown_cbdr), because they sound very similar, and
> they operate on the same data - one is literally a continuation of the
> other. Then I looked downstream where the netc_switch is another API
> user of netc_setup_cbdr() and netc_teardown_cbdr().
> 
> Do you think you could rename netc_setup_cbdr() into something like below:

Sure, I will rename them.

> 
> struct ntmp_user *ntmp_user_create(struct device *dev, size_t num_cbdr,
> 				   const struct netc_cbdr_regs *regs);
> void ntmp_user_destroy(struct ntmp_user *user);
> 
> From a data encapsulation perspective, it would be great if the outside
> world only worked with an opaque struct ntmp_user * pointer.
> 
> Hide NETC_CBDR_BD_NUM from include/linux/fsl/ntmp.h if API users don't
> need to customize it, and let ntmp_user_create() set it.
> 

Do we need to retain cbdr_size in struct ntmp_user? Or just remove it in
next version?