linux-kernel - Re: [PATCH v9 2/2] phy: Add driver for mixel mipi dphy found on NXP's i.MX8 SoCs

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Date:   Tue, 30 Apr 2019 18:58:17 +0200
From:   Guido Günther <agx@...xcpu.org>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        Thierry Reding <treding@...dia.com>,
        Andreas Färber <afaerber@...e.de>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Johan Hovold <johan@...nel.org>,
        Lucas Stach <l.stach@...gutronix.de>,
        Abel Vesa <abel.vesa@....com>, Li Jun <jun.li@....com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        DRI mailing list <dri-devel@...ts.freedesktop.org>,
        Robert Chiras <robert.chiras@....com>,
        Sam Ravnborg <sam@...nborg.org>,
        Maxime Ripard <maxime.ripard@...tlin.com>
Subject: Re: [PATCH v9 2/2] phy: Add driver for mixel mipi dphy found on
 NXP's i.MX8 SoCs

Hi Fabio,
On Tue, Apr 30, 2019 at 01:24:45PM -0300, Fabio Estevam wrote:
> Hi Guido,
> 
> On Tue, Apr 30, 2019 at 11:40 AM Guido Günther <agx@...xcpu.org> wrote:
> >
> > This adds support for the Mixel DPHY as found on i.MX8 CPUs but since
> > this is an IP core it will likely be found on others in the future. So
> > instead of adding this to the nwl host driver make it a generic PHY
> > driver.
> >
> > The driver supports the i.MX8MQ. Support for i.MX8QM and i.MX8QXP can be
> > added once the necessary system controller bits are in via
> > mixel_dphy_devdata.
> >
> > Co-authored-by: Robert Chiras <robert.chiras@....com>
> > Signed-off-by: Guido Günther <agx@...xcpu.org>
> 
> I wish I could test it on a imx8m-evk , but there are some other
> pieces needed such as Northwest Logic driver, mxsfb changes for
> supporting mx8m, OLED panel driver, etc
> 
> Anyway, it looks good to me and I have only a few minor comments:
> 
> > ---
> >  drivers/phy/freescale/Kconfig                 |  11 +
> >  drivers/phy/freescale/Makefile                |   1 +
> >  .../phy/freescale/phy-fsl-imx8-mipi-dphy.c    | 506 ++++++++++++++++++
> >  3 files changed, 518 insertions(+)
> >  create mode 100644 drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> >
> > diff --git a/drivers/phy/freescale/Kconfig b/drivers/phy/freescale/Kconfig
> > index 832670b4952b..a111b130f9d2 100644
> > --- a/drivers/phy/freescale/Kconfig
> > +++ b/drivers/phy/freescale/Kconfig
> > @@ -3,3 +3,14 @@ config PHY_FSL_IMX8MQ_USB
> >         depends on OF && HAS_IOMEM
> >         select GENERIC_PHY
> >         default ARCH_MXC && ARM64
> > +
> > +config PHY_MIXEL_MIPI_DPHY
> > +       tristate "Mixel MIPI DSI PHY support"
> > +       depends on OF && HAS_IOMEM
> > +       select GENERIC_PHY
> > +       select GENERIC_PHY_MIPI_DPHY
> > +       select REGMAP_MMIO
> > +       default ARCH_MXC && ARM64
> 
> I don't think that this default is a good idea.
> 
> There are imx8m systems that do not have display, so in this case it
> does not make sense to always force the build of this driver.

O.k. - we can enable this based on imx-nwl later on. I've also addressed
your other comments. Will wait for a v10 for a couple of days in case
there's more feedback.
Thanks,
 -- Guido