[PATCH v18 6/8] phy: freescale: Add DisplayPort/HDMI Combo-PHY driver for i.MX8MQ

[Dmitry Baryshkov]

On Tue, Nov 05, 2024 at 02:05:51PM +0000, Sandor Yu wrote:
> > 
> > On Tue, Oct 29, 2024 at 02:02:14PM +0800, Sandor Yu wrote:
> > > Add Cadence HDP-TX DisplayPort and HDMI PHY driver for i.MX8MQ.
> > >
> > > Cadence HDP-TX PHY could be put in either DP mode or
> > > HDMI mode base on the configuration chosen.
> > > DisplayPort or HDMI PHY mode is configured in the driver.
> > >
> > > Signed-off-by: Sandor Yu <Sandor.yu at nxp.com>
> > > Signed-off-by: Alexander Stein <alexander.stein at ew.tq-group.com>
> > > ---
> > > v17->v18:
> > > - fix build error as code rebase to latest kernel version.
> > >
> > >  drivers/phy/freescale/Kconfig                |   10 +
> > >  drivers/phy/freescale/Makefile               |    1 +
> > >  drivers/phy/freescale/phy-fsl-imx8mq-hdptx.c | 1337
> > ++++++++++++++++++
> > >  3 files changed, 1348 insertions(+)
> > >  create mode 100644 drivers/phy/freescale/phy-fsl-imx8mq-hdptx.c
> > >
> > > diff --git a/drivers/phy/freescale/Kconfig b/drivers/phy/freescale/Kconfig
> > > index dcd9acff6d01a..2b1210367b31c 100644
> > > --- a/drivers/phy/freescale/Kconfig
> > > +++ b/drivers/phy/freescale/Kconfig

[...]

I'm sorry, my email client cut the email.

> > > +static int cdns_hdptx_dp_configure(struct phy *phy,
> > > +                                union phy_configure_opts *opts)
> > > +{
> > > +     struct cdns_hdptx_phy *cdns_phy = phy_get_drvdata(phy);
> > > +
> > > +     cdns_phy->dp.link_rate = opts->dp.link_rate;
> > > +     cdns_phy->dp.lanes = opts->dp.lanes;
> > 
> > Shouldn't this be conditional on set_rate / set_lanes ?
> 
> PHY do not support reconfigure link rate and lane count.

So, you don't support reconfiguring the rate / count, but you still copy
the new rate and lanes into your driver data. That sounds strange.

[...]

> 
> > 
> > > +
> > > +static int cdns_hdptx_phy_set_mode(struct phy *phy, enum phy_mode
> > mode, int submode)
> > > +{
> > > +     struct cdns_hdptx_phy *cdns_phy = phy_get_drvdata(phy);
> > > +     int ret = 0;
> > > +
> > > +     if (mode == PHY_MODE_DP) {
> > > +             hdptx_dp_phy_ref_clock_type(cdns_phy);
> > > +
> > > +             /* PHY power up */
> > > +             ret = hdptx_dp_phy_power_up(cdns_phy);
> > > +             if (ret < 0)
> > > +                     return ret;
> > > +
> > > +             hdptx_dp_aux_cfg(cdns_phy);
> > 
> > Why? Don't power up the PHY if you haven't been told to.
> 
> Power on the PHY to enable DP AUX, which is necessary for reading EDID and training the link.

Call phy_power_on() from the DP driver.

> 
> > 
> > > +     } else if (mode != PHY_MODE_HDMI) {
> > > +             dev_err(&phy->dev, "Invalid PHY mode: %u\n", mode);
> > > +             return -EINVAL;
> > > +     }
> > > +
> > > +     return ret;
> > > +}
> > > +
> > > +static int cdns_hdptx_hdmi_configure(struct phy *phy,
> > > +                                  union phy_configure_opts
> > *opts)
> > > +{
> > > +     struct cdns_hdptx_phy *cdns_phy = phy_get_drvdata(phy);
> > > +     int ret;
> > > +
> > > +     cdns_phy->hdmi.tmds_char_rate = opts->hdmi.tmds_char_rate;
> > > +
> > > +     /* Check HDMI FW alive before HDMI PHY init */
> > > +     ret = hdptx_phy_check_alive(cdns_phy);
> > > +     if (!ret) {
> > > +             dev_err(cdns_phy->dev, "NO HDMI FW running\n");
> > > +             return -ENXIO;
> > > +     }
> > > +
> > > +     /* Configure PHY */
> > > +     if (hdptx_hdmi_phy_cfg(cdns_phy, cdns_phy->hdmi.tmds_char_rate)
> > < 0) {
> > > +             dev_err(cdns_phy->dev, "failed to set phy pclock\n");
> > > +             return -EINVAL;
> > > +     }
> > > +
> > > +     ret = hdptx_hdmi_phy_power_up(cdns_phy);
> > 
> > it seems to be all over the place :-(
> 
> The PHY has different power-up rules depending on whether it's in DP or HDMI mode. 
> In DP mode, it needs to power up first to enable DP AUX. 
> In HDMI mode, it can power up last.

The main question is why are you powering the PHY from the configure
path at all? There is a phy_power_on() API which should be used by your
HDMI / DP driver instead of handling that in an automagic way.

> 

-- 
With best wishes
Dmitry