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). > > 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. > > 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] [1] https://lore.kernel.org/all/CAMty3ZD7eFi4o7ZXNtjShoLd5yj3wn85Fm6ZNL89=QpWj44KPw@xxxxxxxxxxxxxx/T/ [2] https://patchwork.kernel.org/project/dri-devel/patch/20230218111712.2380225-6-treapking@xxxxxxxxxxxx/ [3] https://indico.freedesktop.org/event/2/contributions/76/ [4] https://www.youtube.com/watch?v=PoYdP9fPn-4&t=624s Thanks, Jagan.
