netdev - RE: [PATCH net-next v5 2/5] net: phy: microchip_ptp : Add ptp library for Microchip phys

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Message-ID:
 <CO1PR11MB4771822A51BEBDEFF9F51B11E2302@CO1PR11MB4771.namprd11.prod.outlook.com>
Date: Thu, 5 Dec 2024 11:26:04 +0000
From: <Divya.Koppera@...rochip.com>
To: <pabeni@...hat.com>, <andrew@...n.ch>, <Arun.Ramadoss@...rochip.com>,
	<UNGLinuxDriver@...rochip.com>, <hkallweit1@...il.com>,
	<linux@...linux.org.uk>, <davem@...emloft.net>, <edumazet@...gle.com>,
	<kuba@...nel.org>, <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<richardcochran@...il.com>, <vadim.fedorenko@...ux.dev>
Subject: RE: [PATCH net-next v5 2/5] net: phy: microchip_ptp : Add ptp library
 for Microchip phys

Hi Paolo Abeni,

Thanks for your quick response.

> -----Original Message-----
> From: Paolo Abeni <pabeni@...hat.com>
> Sent: Thursday, December 5, 2024 4:38 PM
> To: Divya Koppera - I30481 <Divya.Koppera@...rochip.com>;
> andrew@...n.ch; Arun Ramadoss - I17769
> <Arun.Ramadoss@...rochip.com>; UNGLinuxDriver
> <UNGLinuxDriver@...rochip.com>; hkallweit1@...il.com;
> linux@...linux.org.uk; davem@...emloft.net; edumazet@...gle.com;
> kuba@...nel.org; netdev@...r.kernel.org; linux-kernel@...r.kernel.org;
> richardcochran@...il.com; vadim.fedorenko@...ux.dev
> Subject: Re: [PATCH net-next v5 2/5] net: phy: microchip_ptp : Add ptp library
> for Microchip phys
> 
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> content is safe
> 
> On 12/5/24 12:00, Divya.Koppera@...rochip.com wrote:
> > From: Paolo Abeni <pabeni@...hat.com> Thursday, December 5, 2024 3:17
> > PM
> >> To: Divya Koppera - I30481 <Divya.Koppera@...rochip.com>;
> >> andrew@...n.ch; Arun Ramadoss - I17769
> <Arun.Ramadoss@...rochip.com>;
> >> UNGLinuxDriver <UNGLinuxDriver@...rochip.com>;
> hkallweit1@...il.com;
> >> linux@...linux.org.uk; davem@...emloft.net; edumazet@...gle.com;
> >> kuba@...nel.org; netdev@...r.kernel.org;
> >> linux-kernel@...r.kernel.org; richardcochran@...il.com;
> >> vadim.fedorenko@...ux.dev
> >> Subject: Re: [PATCH net-next v5 2/5] net: phy: microchip_ptp : Add
> >> ptp library for Microchip phys
> >>
> >> EXTERNAL EMAIL: Do not click links or open attachments unless you
> >> know the content is safe
> >>
> >> On 12/3/24 09:52, Divya Koppera wrote:
> >>> +struct mchp_ptp_clock *mchp_ptp_probe(struct phy_device *phydev,
> u8
> >> mmd,
> >>> +                                   u16 clk_base_addr, u16
> >>> +port_base_addr) {
> >>> +     struct mchp_ptp_clock *clock;
> >>> +     int rc;
> >>> +
> >>> +     clock = devm_kzalloc(&phydev->mdio.dev, sizeof(*clock),
> GFP_KERNEL);
> >>> +     if (!clock)
> >>> +             return ERR_PTR(-ENOMEM);
> >>> +
> >>> +     clock->port_base_addr   = port_base_addr;
> >>> +     clock->clk_base_addr    = clk_base_addr;
> >>> +     clock->mmd              = mmd;
> >>> +
> >>> +     /* Register PTP clock */
> >>> +     clock->caps.owner          = THIS_MODULE;
> >>> +     snprintf(clock->caps.name, 30, "%s", phydev->drv->name);
> >>> +     clock->caps.max_adj        = MCHP_PTP_MAX_ADJ;
> >>> +     clock->caps.n_ext_ts       = 0;
> >>> +     clock->caps.pps            = 0;
> >>> +     clock->caps.adjfine        = mchp_ptp_ltc_adjfine;
> >>> +     clock->caps.adjtime        = mchp_ptp_ltc_adjtime;
> >>> +     clock->caps.gettime64      = mchp_ptp_ltc_gettime64;
> >>> +     clock->caps.settime64      = mchp_ptp_ltc_settime64;
> >>> +     clock->ptp_clock = ptp_clock_register(&clock->caps,
> >>> +                                           &phydev->mdio.dev);
> >>> +     if (IS_ERR(clock->ptp_clock))
> >>> +             return ERR_PTR(-EINVAL);
> >>> +
> >>> +     /* Initialize the SW */
> >>> +     skb_queue_head_init(&clock->tx_queue);
> >>> +     skb_queue_head_init(&clock->rx_queue);
> >>> +     INIT_LIST_HEAD(&clock->rx_ts_list);
> >>> +     spin_lock_init(&clock->rx_ts_lock);
> >>> +     mutex_init(&clock->ptp_lock);
> >>
> >> The s/w initialization is completed after successfully registering
> >> the new ptp clock, is that safe? It looks like it may race with ptp callbacks.
> >
> > If I understand your comment correctly ptp_lock in the clock instance is not
> initialized before registering the clock.
> > Rest of the initializations are related to packet processing and also depends
> on phydev->default_timestamp and mii_ts instance only after which packets
> will be forwarded to phy.
> > As we are also re-initializing the clock ptp4l/application need to restart.
> >
> > Initializing ptp_lock before registering the clock should be safe from ptp point
> of view.
> >
> > Let me know your opinion?
> 
> I guess moving the lock initialization before the registration should be safe.
> 

Okay. Will fix it in next version.

> Please not that the main issue open is WRT code reuse: I second Andrew
> opinion about the need of consolidating the microchip ptp drivers
> implementation. A library should be able to abstract above individual device
> differences.
> 

This current library implementation is for all the future Microchip PHYs which will be using the same IP.

> Thanks,
> 
> Paolo

Thanks,
Divya