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

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Message-ID:
 <PAXPR04MB94488E0A549E519CEB8AA40EF43C2@PAXPR04MB9448.eurprd04.prod.outlook.com>
Date: Mon, 9 Dec 2024 08:16:48 +0000
From: Sandor Yu <sandor.yu@....com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
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>,
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	<dri-devel@...ts.freedesktop.org>, "devicetree@...r.kernel.org"
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	<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: [EXT] Re: [PATCH v18 6/8] phy: freescale: Add DisplayPort/HDMI
 Combo-PHY driver for i.MX8MQ



> -----Original Message-----
> From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Sent: 2024年11月30日 16:30
> To: Sandor Yu <sandor.yu@....com>
> Cc: andrzej.hajda@...el.com; neil.armstrong@...aro.org; Laurent Pinchart
> <laurent.pinchart@...asonboard.com>; jonas@...boo.se;
> jernej.skrabec@...il.com; airlied@...il.com; daniel@...ll.ch;
> robh+dt@...nel.org; krzysztof.kozlowski+dt@...aro.org;
> shawnguo@...nel.org; s.hauer@...gutronix.de; festevam@...il.com;
> vkoul@...nel.org; dri-devel@...ts.freedesktop.org;
> devicetree@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org; linux-phy@...ts.infradead.org;
> mripard@...nel.org; kernel@...gutronix.de; dl-linux-imx
> <linux-imx@....com>; Oliver Brown <oliver.brown@....com>;
> alexander.stein@...tq-group.com; sam@...nborg.org
> Subject: Re: [EXT] Re: [PATCH v18 6/8] phy: freescale: Add DisplayPort/HDMI
> Combo-PHY driver for i.MX8MQ
> 
> Caution: This is an external email. Please take care when clicking links or
> opening attachments. When in doubt, report the message using the 'Report
> this email' button
> 
> 
> On Tue, Nov 26, 2024 at 02:12:19PM +0000, Sandor Yu wrote:
> >
> > >
> > > 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.
> >
> > The PHY will use link rate and lane count to configure its registers
> 
> I'm not sure if I follow it. Do you mean that rate / count configuration is static?

In DP controller driver, rate and lane count are determined during link training. 
These two parameters are fixed in the DP PHY driver and cannot be modified.

Sandor

> 
> --
> With best wishes
> Dmitry