Re: [PATCH 17/22] phy: qcom-qmp-combo: merge USB and DP configurations

[Dmitry Baryshkov]

On 14/11/2022 11:54, Johan Hovold wrote:
> On Sat, Nov 12, 2022 at 10:43:14AM +0300, Dmitry Baryshkov wrote:
> > On 11/11/2022 11:56, Johan Hovold wrote:
> > > It does not really make any sense to keep separate configuration
> > > structures for the USB and DP parts of the same PHY so merge them.
> > >
> > > Signed-off-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
> > > ---
> > >    drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 182 +++++++---------------
> > >    1 file changed, 57 insertions(+), 125 deletions(-)
> > >
> > > diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> > > index b27d1821116c..249912b75964 100644
> > > --- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> > > +++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> > > @@ -798,10 +798,7 @@ static const u8 qmp_dp_v5_voltage_swing_hbr_rbr[4][4] = {
> > >    
> > >    struct qmp_phy;
> > >    
> > > -/* struct qmp_phy_cfg - per-PHY initialization config */
> > >    struct qmp_phy_cfg {
> > > -	/* phy-type - PCIE/UFS/USB */
> > > -	unsigned int type;
> > >    	int lanes;
> >
> > int lanes doesn't really make sense here in my opinion. It should be
> > usb_lanes and dp_lanes.
>
> It doesn't make much less sense than having it here currently do.
>
> All of these USB-C PHYs are dual lane for bi-directional SS USB and
> quad lane for uni-directional DP (even if only CC1 orientation and lanes
> 2 and 3 are currently supported).

I was under impression that sdm845 has just a single lane for each of 
USB and DP. After rechecking the phy/next, I see that it was my mistake 
(quite logical, SS is two lanes, so the compliant PHY must have two 
lanes too).

I wander how/if 4-lane DP works. The only thing that we do is 
programming of the QSERDES_DP_PHY_PD_CTL register, however judging e.g. 
your 4-lane PCIe changes, one should probably also program the other two 
lanes. Maybe it is handled automatically inside the hardware.

> I should probably just drop the lanes parameter completely, either as a
> preparatory clean up or as follow-on one (e.g. also a bit depending on
> if there are other reasons for respinning a v2).

I think a follow up is enough, but let's get it. Having a single lanes=2 
field looks... strange.

--
With best wishes
Dmitry