On Fri, Jan 03, 2025 at 12:22:34AM +0100, Marek Vasut wrote:
> On 1/2/25 5:55 AM, Dmitry Baryshkov wrote:
> > On Tue, Dec 31, 2024 at 08:28:49PM +0100, Marek Vasut wrote:
> > > The dw-hdmi output_port is set to 1 in order to look for a connector
> > > next bridge in order to get DRM_BRIDGE_ATTACH_NO_CONNECTOR working.
> > > The output_port set to 1 makes the DW HDMI driver core look up the
> > > next bridge in DT, where the next bridge is often the hdmi-connector .
> > >
> > > Similar to 0af5e0b41110 ("drm/meson: encoder_hdmi: switch to bridge DRM_BRIDGE_ATTACH_NO_CONNECTOR")
> > >
> > > Note that looking at the upstream arch/arm64/boot/dts/freescale/imx8mp*dts ,
> > > the oldest commit which adds HDMI support is commit:
> > >
> > > 3e67a1ddd56d ("arm64: dts: imx8mp: Enable HDMI on TQMa8MPxL/MBa8MPxL")
> > >
> > > That already contains the HDMI connector node. Most follow up additions
> > > of HDMI support to another devices has been a variation of the same commit,
> > > including connector node, which is the proper way of eanbling HDMI on the
> > > i.MX8MP.
> > >
> > > The rest should be covered by output_port_optional which should make systems
> > > with DTs without HDMI connector node work, but such DTs should be updated and
> > > the HDMI connector node should be added.
> > >
> > > Signed-off-by: Marek Vasut <marex@xxxxxxx>
> > > ---
> > > Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
> > > Cc: David Airlie <airlied@xxxxxxxxx>
> > > Cc: Fabio Estevam <festevam@xxxxxxxxx>
> > > Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
> > > Cc: Jonas Karlman <jonas@xxxxxxxxx>
> > > Cc: Laurent Pinchart <Laurent.pinchart@xxxxxxxxxxxxxxxx>
> > > Cc: Liu Ying <victor.liu@xxxxxxx>
> > > Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> > > Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> > > Cc: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
> > > Cc: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>
> > > Cc: Robert Foss <rfoss@xxxxxxxxxx>
> > > Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> > > Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
> > > Cc: Simona Vetter <simona@xxxxxxxx>
> > > Cc: Stefan Agner <stefan@xxxxxxxx>
> > > Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > > Cc: imx@xxxxxxxxxxxxxxx
> > > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > > ---
> > > V2: No change
> > > V3: - Update commit message
> > > - Move select DRM_DISPLAY_CONNECTOR to DRM_IMX8MP_DW_HDMI_BRIDGE
> > > - Enable output_port_optional
> > > ---
> > > drivers/gpu/drm/bridge/imx/Kconfig | 1 +
> > > drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c | 2 ++
> > > 2 files changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/bridge/imx/Kconfig b/drivers/gpu/drm/bridge/imx/Kconfig
> > > index 9a480c6abb856..db5c8a76193ac 100644
> > > --- a/drivers/gpu/drm/bridge/imx/Kconfig
> > > +++ b/drivers/gpu/drm/bridge/imx/Kconfig
> > > @@ -17,6 +17,7 @@ config DRM_IMX8MP_DW_HDMI_BRIDGE
> > > tristate "Freescale i.MX8MP HDMI-TX bridge support"
> > > depends on OF
> > > depends on COMMON_CLK
> > > + select DRM_DISPLAY_CONNECTOR
> >
> > I was going to write that it is not to be selected by anybody, but then
> > I stumbled upon meson driver, which also selects the symbol.
> >
> > I still think that it is not to be selected by your driver as there is
> > no direct dependency (and there can be other bridges inbetween or the
> > bridge chain can end up with some other bridge). Such decisions belong
> > to defconfig or distribution's kernel config file.
> Wouldn't that only lead to unnecessary surprises on user side ?
This is of no concerns to Kconfig. You can't select all drivers that can
possibly be used with your platform / driver. `git grep
DRM_DISPLAY_CONNECTOR`.
--
With best wishes
Dmitry
