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Message-ID: <z6p6bewmykmufsghdojr4lvziurmmfpnrr5m4w3pfjlqzobpwr@zq2d2ukjvtac>
Date: Thu, 7 Nov 2024 15:43:20 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Sandor Yu <sandor.yu@....com>
Cc: "andrzej.hajda@...el.com" <andrzej.hajda@...el.com>,
"neil.armstrong@...aro.org" <neil.armstrong@...aro.org>, Laurent Pinchart <laurent.pinchart@...asonboard.com>,
"jonas@...boo.se" <jonas@...boo.se>, "jernej.skrabec@...il.com" <jernej.skrabec@...il.com>,
"airlied@...il.com" <airlied@...il.com>, "daniel@...ll.ch" <daniel@...ll.ch>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>, "shawnguo@...nel.org" <shawnguo@...nel.org>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>, "festevam@...il.com" <festevam@...il.com>,
"vkoul@...nel.org" <vkoul@...nel.org>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>, "mripard@...nel.org" <mripard@...nel.org>,
"kernel@...gutronix.de" <kernel@...gutronix.de>, dl-linux-imx <linux-imx@....com>,
Oliver Brown <oliver.brown@....com>,
"alexander.stein@...tq-group.com" <alexander.stein@...tq-group.com>, "sam@...nborg.org" <sam@...nborg.org>
Subject: Re: [PATCH v18 6/8] phy: freescale: Add DisplayPort/HDMI Combo-PHY
driver for i.MX8MQ
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@....com>
> > > Signed-off-by: Alexander Stein <alexander.stein@...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
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