netdev - RE: [net-next 11/14] ptp: ravb: convert to .adjfine and adjust_by_scaled

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Date:   Mon, 22 Aug 2022 17:07:14 +0000
From:   "Keller, Jacob E" <jacob.e.keller@...el.com>
To:     Sergey Shtylyov <s.shtylyov@....ru>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>,
        "Cui, Dexuan" <decui@...rosoft.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "Siva Reddy Kallam" <siva.kallam@...adcom.com>,
        Prashant Sreedharan <prashant@...adcom.com>,
        Michael Chan <mchan@...adcom.com>,
        Yisen Zhuang <yisen.zhuang@...wei.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
        Tariq Toukan <tariqt@...dia.com>,
        "Saeed Mahameed" <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>,
        "Bryan Whitehead" <bryan.whitehead@...rochip.com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Richard Cochran <richardcochran@...il.com>,
        "Thampi, Vivek" <vithampi@...are.com>,
        VMware PV-Drivers Reviewers <pv-drivers@...are.com>,
        Jie Wang <wangjie125@...wei.com>,
        Guangbin Huang <huangguangbin2@...wei.com>,
        Eran Ben Elisha <eranbe@...dia.com>,
        Aya Levin <ayal@...dia.com>,
        Cai Huoqing <cai.huoqing@...ux.dev>,
        Biju Das <biju.das.jz@...renesas.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        Jiasheng Jiang <jiasheng@...as.ac.cn>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Wan Jiabing <wanjiabing@...o.com>,
        Lv Ruyi <lv.ruyi@....com.cn>, Arnd Bergmann <arnd@...db.de>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>
Subject: RE: [net-next 11/14] ptp: ravb: convert to .adjfine and
 adjust_by_scaled_ppm



> -----Original Message-----
> From: Sergey Shtylyov <s.shtylyov@....ru>
> Sent: Saturday, August 20, 2022 12:34 PM
> To: Keller, Jacob E <jacob.e.keller@...el.com>; netdev@...r.kernel.org
> Cc: K. Y. Srinivasan <kys@...rosoft.com>; Haiyang Zhang
> <haiyangz@...rosoft.com>; Stephen Hemminger <sthemmin@...rosoft.com>;
> Wei Liu <wei.liu@...nel.org>; Cui, Dexuan <decui@...rosoft.com>; Tom
> Lendacky <thomas.lendacky@....com>; Shyam Sundar S K <Shyam-sundar.S-
> k@....com>; David S. Miller <davem@...emloft.net>; Eric Dumazet
> <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>; Paolo Abeni
> <pabeni@...hat.com>; Siva Reddy Kallam <siva.kallam@...adcom.com>;
> Prashant Sreedharan <prashant@...adcom.com>; Michael Chan
> <mchan@...adcom.com>; Yisen Zhuang <yisen.zhuang@...wei.com>; Salil
> Mehta <salil.mehta@...wei.com>; Brandeburg, Jesse
> <jesse.brandeburg@...el.com>; Nguyen, Anthony L
> <anthony.l.nguyen@...el.com>; Tariq Toukan <tariqt@...dia.com>; Saeed
> Mahameed <saeedm@...dia.com>; Leon Romanovsky <leon@...nel.org>;
> Bryan Whitehead <bryan.whitehead@...rochip.com>; Giuseppe Cavallaro
> <peppe.cavallaro@...com>; Alexandre Torgue <alexandre.torgue@...s.st.com>;
> Jose Abreu <joabreu@...opsys.com>; Maxime Coquelin
> <mcoquelin.stm32@...il.com>; Richard Cochran <richardcochran@...il.com>;
> Thampi, Vivek <vithampi@...are.com>; VMware PV-Drivers Reviewers <pv-
> drivers@...are.com>; Jie Wang <wangjie125@...wei.com>; Guangbin Huang
> <huangguangbin2@...wei.com>; Eran Ben Elisha <eranbe@...dia.com>; Aya
> Levin <ayal@...dia.com>; Cai Huoqing <cai.huoqing@...ux.dev>; Biju Das
> <biju.das.jz@...renesas.com>; Lad Prabhakar <prabhakar.mahadev-
> lad.rj@...renesas.com>; Phil Edworthy <phil.edworthy@...esas.com>; Jiasheng
> Jiang <jiasheng@...as.ac.cn>; Gustavo A. R. Silva <gustavoars@...nel.org>; Linus
> Walleij <linus.walleij@...aro.org>; Wan Jiabing <wanjiabing@...o.com>; Lv Ruyi
> <lv.ruyi@....com.cn>; Arnd Bergmann <arnd@...db.de>; linux-renesas-
> soc@...r.kernel.org
> Subject: Re: [net-next 11/14] ptp: ravb: convert to .adjfine and
> adjust_by_scaled_ppm
> 
> Hello!
> 
> On 8/19/22 1:27 AM, Jacob Keller wrote:
> 
> > The ravb implementation of .adjfreq is implemented in terms of a
> > straight forward "base * ppb / 1 billion" calculation.
> >
> > Convert this driver to .adjfine and use the adjust_by_scaled_ppm helper
> > function to calculate the new addend.
> >
> > Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
> > Cc: Sergey Shtylyov <s.shtylyov@....ru>
> > Cc: Biju Das <biju.das.jz@...renesas.com>
> > Cc: Phil Edworthy <phil.edworthy@...esas.com>
> > Cc: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > Cc: linux-renesas-soc@...r.kernel.org
> > ---
> >
> > I do not have this hardware, and have only compile tested the change.
> >
> >  drivers/net/ethernet/renesas/ravb_ptp.c | 16 +++++-----------
> >  1 file changed, 5 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/renesas/ravb_ptp.c
> b/drivers/net/ethernet/renesas/ravb_ptp.c
> > index 87c4306d66ec..941aa3b0e8a0 100644
> > --- a/drivers/net/ethernet/renesas/ravb_ptp.c
> > +++ b/drivers/net/ethernet/renesas/ravb_ptp.c
> > @@ -88,24 +88,18 @@ static int ravb_ptp_update_compare(struct
> ravb_private *priv, u32 ns)
> >  }
> >
> >  /* PTP clock operations */
> > -static int ravb_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
> > +static int ravb_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
> >  {
> >  	struct ravb_private *priv = container_of(ptp, struct ravb_private,
> >  						 ptp.info);
> >  	struct net_device *ndev = priv->ndev;
> >  	unsigned long flags;
> > -	u32 diff, addend;
> > -	bool neg_adj = false;
> > +	u32 addend;
> >  	u32 gccr;
> >
> > -	if (ppb < 0) {
> > -		neg_adj = true;
> > -		ppb = -ppb;
> > -	}
> >  	addend = priv->ptp.default_addend;
> 
>    I don't think we should keep this line -- it has no effect now...
> 

Yea this can be dropped.

> > -	diff = div_u64((u64)addend * ppb, NSEC_PER_SEC);
> > -
> > -	addend = neg_adj ? addend - diff : addend + diff;
> > +	addend = (u32)adjust_by_scaled_ppm(priv->ptp.default_addend,
> > +					   scaled_ppm);
> >
> >  	spin_lock_irqsave(&priv->lock, flags);
> >
> [...]
> 
> MBR, Sergey