linux-kernel - Re: [PATCH v2] drm/bridge: imx: i.MX8 bridge drivers should depend on ARCH

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Message-ID: <9f5b511708ca9b30ef101a46a5d1b76f03b2c4fc.camel@nxp.com>
Date:   Tue, 28 Jun 2022 10:31:32 +0800
From:   Liu Ying <victor.liu@....com>
To:     Neil Armstrong <narmstrong@...libre.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Robert Foss <robert.foss@...aro.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Marek Vasut <marex@...x.de>
Cc:     dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/bridge: imx: i.MX8 bridge drivers should depend
 on ARCH_MXC

On Mon, 2022-06-27 at 14:22 +0200, Neil Armstrong wrote:
> Hi,

Hi,

> 
> On 24/06/2022 14:10, Geert Uytterhoeven wrote:
> > The various Freescale i.MX8 display bridges are only present on
> > Freescale i.MX8 SoCs.  Hence add a dependency on ARCH_MXC, to
> > prevent
> > asking the user about these drivers when configuring a kernel
> > without
> > i.MX SoC support.
> > 
> > Fixes: e60c4354840b2fe8 ("drm/bridge: imx: Add LDB support for
> > i.MX8qm")
> > Fixes: 3818715f62b42b5c ("drm/bridge: imx: Add LDB support for
> > i.MX8qxp")
> > Fixes: 96988a526c97cfbe ("drm/bridge: imx: Add i.MX8qxp pixel link
> > to DPI support")
> > Fixes: 1ec17c26bc06289d ("drm/bridge: imx: Add i.MX8qm/qxp display
> > pixel link support")
> > Fixes: 93e163a9e0392aca ("drm/bridge: imx: Add i.MX8qm/qxp pixel
> > combiner support")
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> > Reviewed-by: Liu Ying <victor.liu@....com>
> > ---
> > v2:
> >    - s/i.MX8MP/i.MX8/,
> >    - Add Reviewed-by.
> > ---
> >   drivers/gpu/drm/bridge/imx/Kconfig | 4 ++++
> >   1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/bridge/imx/Kconfig
> > b/drivers/gpu/drm/bridge/imx/Kconfig
> > index 212a7b0e64fd8b5a..608f47f41bcd1c81 100644
> > --- a/drivers/gpu/drm/bridge/imx/Kconfig
> > +++ b/drivers/gpu/drm/bridge/imx/Kconfig
> > @@ -1,3 +1,5 @@
> > +if ARCH_MXC || COMPILE_TEST
> > +
> >   config DRM_IMX8QM_LDB
> >   	tristate "Freescale i.MX8QM LVDS display bridge"
> >   	depends on OF
> > @@ -41,3 +43,5 @@ config DRM_IMX8QXP_PIXEL_LINK_TO_DPI
> >   	help
> >   	  Choose this to enable pixel link to display pixel
> > interface(PXL2DPI)
> >   	  found in Freescale i.MX8qxp processor.
> > +
> > +endif # ARCH_MXC || COMPILE_TEST
> 
> I was wondering why those were added in drivers/gpu/drm/bridge/imx
> since they are specific to NXP SoCs,
> I think they should be moved in the right drm imx subsystem instead
> of this change.

There are 2 directories which contain display controller drivers for
i.MX SoCs:
a. drivers/gpu/drm/imx - i.MX51/53/6qdl IPUv3, i.MX8mq DCSS and
   i.MX8qm/qxp DPU([1], not landed yet)
b. drivers/gpu/drm/mxsfb - i.MX23/28/6sx/8mq LCDIF and i.MX8mp
   LCDIFv3([2], not landed yet)

Bridges added in drivers/gpu/drm/bridge/imx make it possible to share
bridge drivers across display controllers.  I see chance to use the
LVDS Display Bridge(LDB) helper(imx-ldb-helper.c) for i.MX6sx LDB.

[1] 
https://patchwork.kernel.org/project/dri-devel/patch/20220407091156.1211923-6-victor.liu@nxp.com/
[2] 
https://patchwork.kernel.org/project/dri-devel/patch/20220624180201.150417-2-marex@denx.de/

Regards,
Liu Ying