netdev - Re: [PATCH v2 net-next 3/7] net: dsa: sja1105: Switch to hardware operations for PTP

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Message-Id: <20190912.121203.1106283271122334199.davem@davemloft.net>
Date:   Thu, 12 Sep 2019 12:12:03 +0200 (CEST)
From:   David Miller <davem@...emloft.net>
To:     olteanv@...il.com
Cc:     f.fainelli@...il.com, vivien.didelot@...il.com, andrew@...n.ch,
        richardcochran@...il.com, netdev@...r.kernel.org
Subject: Re: [PATCH v2 net-next 3/7] net: dsa: sja1105: Switch to hardware
 operations for PTP

From: Vladimir Oltean <olteanv@...il.com>
Date: Tue, 10 Sep 2019 04:34:57 +0300

>  static int sja1105_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
>  {
>  	struct sja1105_private *priv = ptp_to_sja1105(ptp);
> +	const struct sja1105_regs *regs = priv->info->regs;
>  	s64 clkrate;
> +	int rc;
 ..
> -static int sja1105_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
> -{
> -	struct sja1105_private *priv = ptp_to_sja1105(ptp);
> +	rc = sja1105_spi_send_int(priv, SPI_WRITE, regs->ptpclkrate,
> +				  &clkrate, 4);

You're sending an arbitrary 4 bytes of a 64-bit value.  This works on little endian
but will not on big endian.

Please properly copy this clkrate into a "u32" variable and pass that into
sja1105_spi_send_int().

It also seems to suggest that you want to use abs() to perform that weird
centering around 1 << 31 calculation.

Thank you.