netdev - Re: [net-next 14/14] ptp: xgbe: convert to .adjfine and adjust_by_scaled

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Date:   Fri, 19 Aug 2022 11:05:25 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Jacob Keller <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>, Dexuan Cui <decui@...rosoft.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>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <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>,
        Sergey Shtylyov <s.shtylyov@....ru>,
        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>,
        Vivek Thampi <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>
Subject: Re: [net-next 14/14] ptp: xgbe: convert to .adjfine and
 adjust_by_scaled_ppm

On 8/18/22 17:27, Jacob Keller wrote:
> The xgbe implementation of .adjfreq is implemented in terms of a
> straight forward "base * ppb / 1 billion" calculation.
> 
> Convert this driver to .adjfine and use adjust_by_scaled_ppm to calculate
> the new addend value.
> 
> Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Cc: Shyam Sundar S K <Shyam-sundar.S-k@....com>
> ---
> 
> I do not have this hardware, and have only compile tested the change.
> 
>   drivers/net/ethernet/amd/xgbe/xgbe-ptp.c | 20 ++++----------------
>   1 file changed, 4 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-ptp.c b/drivers/net/ethernet/amd/xgbe/xgbe-ptp.c
> index d06d260cf1e2..7051bd7cf6dc 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-ptp.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-ptp.c
> @@ -134,27 +134,15 @@ static u64 xgbe_cc_read(const struct cyclecounter *cc)
>   	return nsec;
>   }
>   
> -static int xgbe_adjfreq(struct ptp_clock_info *info, s32 delta)
> +static int xgbe_adjfine(struct ptp_clock_info *info, long scaled_ppm)
>   {
>   	struct xgbe_prv_data *pdata = container_of(info,
>   						   struct xgbe_prv_data,
>   						   ptp_clock_info);
>   	unsigned long flags;
> -	u64 adjust;
> -	u32 addend, diff;
> -	unsigned int neg_adjust = 0;
> +	u64 addend;
>   
> -	if (delta < 0) {
> -		neg_adjust = 1;
> -		delta = -delta;
> -	}
> -
> -	adjust = pdata->tstamp_addend;
> -	adjust *= delta;
> -	diff = div_u64(adjust, 1000000000UL);
> -
> -	addend = (neg_adjust) ? pdata->tstamp_addend - diff :
> -				pdata->tstamp_addend + diff;
> +	addend = adjust_by_scaled_ppm(pdata->tstamp_addend, scaled_ppm);

Since addend is now a u64, but the called function just afterwards, 
xgbe_update_tstamp_addend(), expects an unsigned int, won't this generate 
a compiler warning depending on the flags used?

Thanks,
Tom

>   
>   	spin_lock_irqsave(&pdata->tstamp_lock, flags);
>   
> @@ -235,7 +223,7 @@ void xgbe_ptp_register(struct xgbe_prv_data *pdata)
>   		 netdev_name(pdata->netdev));
>   	info->owner = THIS_MODULE;
>   	info->max_adj = pdata->ptpclk_rate;
> -	info->adjfreq = xgbe_adjfreq;
> +	info->adjfine = xgbe_adjfine;
>   	info->adjtime = xgbe_adjtime;
>   	info->gettime64 = xgbe_gettime;
>   	info->settime64 = xgbe_settime;