Am Donnerstag, 6. April 2023, 11:55:52 CEST schrieb Jagan Teki: > [Replying the Daniel thread since he included bridge maintainers] > > On Thu, Apr 6, 2023 at 2:07 PM Daniel Vetter <daniel@xxxxxxxx> wrote: > > Adding the usual bridge maintainer/review folks since this looks tricky. > > -Daniel > > > > On Thu, 6 Apr 2023 at 10:33, Alexander Stein > > > > <alexander.stein@xxxxxxxxxxxxxxx> wrote: > > > Hi Jagan, > > > > > > thanks for your reply. > > > > > > Am Mittwoch, 5. April 2023, 16:39:07 CEST schrieb Jagan Teki: > > > > On Wed, Apr 5, 2023 at 7:39 PM Alexander Stein > > > > > > > > <alexander.stein@xxxxxxxxxxxxxxx> wrote: > > > > > Hi, > > > > > > > > > > my platform has a DIP switch controlled multiplexer for MIPI DSI > > > > > output > > > > > signals. One output has a TI SN65DSI84 (LVDS) and the other output > > > > > has a > > > > > TI > > > > > SN65DSI86 (eDP) attached to it. The Multiplexer status can be read > > > > > back > > > > > from a GPIO. The GPIO is also IRQ capable, so it would be possible > > > > > to > > > > > support hotplug additionally later on. > > > > > > > > I have this requirement a year back [1] but my design has i.mx8mq DSI > > > > outputs to SN65DSI84(LVDS) and ADV7533 (HDMI) and GPIO has muxed as > > > > IRQ in order to find the bridge selection. (not confused with HDMI > > > > HPD). > > > > > > Looks quite similar. This platform can be used using imx8mq, imx8mm or > > > im8xmn. That mentioned GPIO is also not the HDMI HPD, but connected to > > > a DIP switch on the mainboard to be changed manually. > > So, you need to manually adjust the switch and boot the required > output and the state of the output depends on the set switch gpios > isn't it? do you need to set any gpio so that the required output will > select? That's correct. There is no GPIO I need to set by software for the outputs (despite the enable GPIO on the DSI-to-X bridges, but this is handled in their appropriate drivers). > > > > > My initial idea was to create a DRM multiplexer bridge driver which > > > > > (depending on the input GPIO) allows only one output to be enabled. > > > > > Unfortunately ti- sn65dsi86.c driver expects a DSI host on remote > > > > > node 0 > > > > > (see ti_sn_attach_host and ti_sn_bridge_parse_dsi_host), so it does > > > > > not > > > > > work. ti-sn65dsi83.c just requires a drm_bridge. > > > > > > > > Yes, we need to have a finite amount of pipeline changes. assuming > > > > that your mux bridge sits between DSI to Output interfaces the > > > > proposed mux bridge selects which pipeline. > > > > > > My setup looks like this, but the switch is a different one than yours. > > > > > > | => SN54DSI86 => DP Connector > > > > > > DSI Host => display-switch => | > > > > > > | => SN65DSI83 => Panel-Simple > > This looks correct to me, as I designed the similar one. > > > > > > What is the best approach for this? I currently see two approaches: > > > > > * Create an explicit DSI/DRM multiplexer bridge driver which > > > > > registers > > > > > itself as DSI host > > > > > * Create a DRM multiplexer bridge (only). But this needs to remove > > > > > the DSI > > > > > device registration from ti-sn65dsi86.c > > > > > > > > Based on my experience, having a muxed bridge between in and out would > > > > be proper in order to satisfy the pipeline as well as the design. That > > > > mux bridge has to be a normal bridge doesn't aware of DSI or any other > > > > interface like one of the submissions has done in the recent mailing > > > > list. [2] Things would be complicated when we switch the outputs but > > > > we still use normal static switching of outputs in a proper way. > > > > > > > > > I am aware that DSI support is suboptimal, so I'm not sure which > > > > > approach > > > > > on the TI bridge drivers is the correct one and needs to be > > > > > considered as > > > > > given. Any ideas? > > > > > > > > I did implement some complicated things of switching outputs at > > > > runtime but the idea of the switching pipelines would be similar if > > > > you want to implement it in a normal static way. Here are some details > > > > and a demo of how those been worked. [3] [4] > > > > > > Thanks for the links. From what I read in those discussions dynamically > > > (re)building the bridge chains it not correct/acceptable. Instead two > > > bridges shall be created, but only one connector at the end shall be > > > enabled. This> > > > > would look like this: > > > switched-bridge > > > > > > +------------+ +-------------+ > > > > > > | drm_bridge-|- next_bridge -- | LVDS bridge |- connector > > > | > > > | | +-------------+ > > > > > > in -| | > > > > > > | | +-------------+ > > > | > > > | drm_bridge-|- next_bridge -- | eDP bridge |- connector > > > > > > +------------+ +-------------+ > > > > > > ^ > > > > > > DIP switch > > > > > > But here I'm not so sure how an (hotplug) event (e.g. IRQ) on the > > > switched- > > > bridge can be forwarded to the connectors. But this hotplug event seems > > > to be essential so that DRM master can reconfigure it's output. > > In my opinion, the switched-bridge needs to focus on switching the > outputs based on DIP gpios, and hotplug events need to handle the > associated display bridges like DP, HDMI, etc. It is possible for the > switched-bridge to route the output displays without the hot plug. I agree, IMHO hotplug/HPD events is related to downstream connectors. > Assume the switched-bridge has port 1 and ep 0 connected to LVDS and > port 1 and ep 1 connected to DP. then find and attach them at the > bridge attach function. and do the necessary gpio enablements in > enable or pre_enables. Ah nice. My initial idea was: * port 0 ep 0: input * port 1 ep 0: LVDS * port 2 ep 0: DP But using two endpoints in one port looks neat. Although I'm not sure if there is an actual difference. But if the GPIO check is only done in enable/pre_enable there is no way to support changing the DIP switch aka switched-bridge at runtime. There is nothing the hotplug (non-HPD) event can be sent to, no? Best regards, Alexander -- TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht München, HRB 105018 Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider http://www.tq-group.com/
