linux-kernel - Re: [PATCH v3 4/4] phy: qcom-qmp: new qmp phy driver for qcom-chipsets

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Date:   Fri, 6 Jan 2017 13:17:22 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Vivek Gautam <vivek.gautam@...eaurora.org>
Cc:     robh+dt@...nel.org, kishon@...com, sboyd@...eaurora.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        mark.rutland@....com, srinivas.kandagatla@...aro.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v3 4/4] phy: qcom-qmp: new qmp phy driver for
 qcom-chipsets

On Fri 06 Jan 01:47 PST 2017, Vivek Gautam wrote:

> > > +static int qcom_qmp_phy_com_init(struct qcom_qmp_phy *qphy)
> > > +{
> > > +	const struct qmp_phy_cfg *cfg = qphy->cfg;
> > > +	void __iomem *serdes = qphy->serdes;
> > > +	int ret;
> > > +
> > > +	mutex_lock(&qphy->phy_mutex);
> > > +	if (qphy->init_count++) {
> > > +		mutex_unlock(&qphy->phy_mutex);
> > > +		return 0;
> > > +	}
> > As far as I can see phy_init() and phy_exit() already keep reference
> > count on the initialization and you only call this function from
> > phy_ops->init, so you should be able to drop this.
> This is an intermediary function that does the common block initialization.
> PHYs like PCIe have a separate common block (apart from SerDes)
> for all phy channels. We shouldn't program this common block
> multiple times for each channel. That's why this init_count.
> 

You're right!

Unfortunately it took me several minutes to wrap my head around the phy
vs multi-lane and I have a really hard time keeping "qcom_qmp_phy" and
"qmp_phy_desc" apart throughout the driver.

If I understand correctly the qcom_qmp_phy is the context representing a
"QMP block", while this is a PHY block it's not actually the phy in
Linux eyes. The qcom_phy_desc represents a "QMP lane", which in Linux
eyes is the phys, but as we think of QMP as the PHY this confused me.

How about naming them "struct qmp" and "struct qmp_lane" (or possibly
qmp_phy) instead? That way we remove the confusion of QMP PHY vs Linux
PHY and we make the lane part explicit.

Regards,
Bjorn