Re: [PATCH net-next 4/5] net/fsl: xgmac_mdio: Support setting the MDC frequency

From: Andrew Lunn <andrew@lunn.ch>
To: Tobias Waldekranz <tobias@waldekranz.com>
Cc: davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org,
	Marcin Wojtas <mw@semihalf.com>,
	Calvin Johnson <calvin.johnson@oss.nxp.com>,
	Markus Koch <markus@notsyncing.net>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 4/5] net/fsl: xgmac_mdio: Support setting the MDC frequency
Date: Wed, 26 Jan 2022 15:02:46 +0100	[thread overview]
Message-ID: <YfFUhn+T2SYCaTHc@lunn.ch> (raw)
In-Reply-To: <87r18ubp57.fsf@waldekranz.com>

> >> +	if (device_property_read_u32(dev, "clock-frequency", &priv->mdc_freq))
> >> +		return;
> >> +
> >> +	priv->enet_clk = devm_clk_get(dev, NULL);
> >> +	if (IS_ERR(priv->enet_clk)) {
> >> +		dev_err(dev, "Input clock unknown, not changing MDC frequency");
> >
> > Is the clock optional or mandatory?
> 
> As the code is now, it is mandatory. I could add some default frequency,
> but I fear that could do more harm than good?

As i said in the reply to the DT patch, it is mandatory if the
"clock-frequency" parameter is present.

> Ok, no worries about regressions for deployed stuff already out there?

It would only cause a regression if a DT blob happened to have a
'clock-frequency' parameter and not clock, which it should not.

        Andrew