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

[vivek . gautam]

On 2017-01-07 02:47, Bjorn Andersson wrote:
> 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.

That's correct. The qcom_qmp_phy structure represents the QMP phy block
as a whole and not the individual phy lane instances. These phy lanes
are represented by qcom_phy_desc, and are the actual PHYs in Linux eyes.

> 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.

Sure, this sounds good to me - "struct qmp" and "struct qmp_phy" (will
call the respective variables as qblk for qmp block (struct qmp) and
qphy for struct qmp_phy).
Thanks for pointing out. Will change them.

Regards
Vivek

> Regards,
> Bjorn
>
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