Hi Geert. On Mon, Jan 20, 2020 at 11:10:37AM +0100, Geert Uytterhoeven wrote: > Hi Sam, > > (stumbled on this accidentally) > > On Thu, Aug 2, 2018 at 9:46 PM Sam Ravnborg <sam@xxxxxxxxxxxx> wrote: > > The pardata supports implement a simple bus for devices > > that are connected using a parallel bus driven by GPIOs. > > The is often used in combination with simple displays > > that is often seen in older embedded designs. > > There is a demand for this support also in the linux > > kernel for HW designs that uses these kind of displays. > > > > The pardata bus uses a platfrom_driver that when probed > > creates devices for all child nodes in the DT, > > which are then supposed to be handled by pardata_drivers. > > > > Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx> > > > --- /dev/null > > +++ b/Documentation/driver-api/pardata.rst > > @@ -0,0 +1,60 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +========================= > > +Parallel Data Bus/Drivers > > +========================= > > + > > +Displays may be connected using a simple parallel bus. > > +This is often seen in embedded systems with a simple MCU, but is also > > +used in Linux based systems to a small extent. > > + > > +The bus looks like this: > > + > > +.. code-block:: none > > + > > + ----+ > > + | DB0-DB7 or DB4-DB7 +---- > > + ===/======================== > > + | E - enable | D > > + ---------------------------- I > > + C | Reset | S > > + P ---------------------------- P > > + U | Read/Write (one or two) | L > > + ---------------------------- A > > + | RS - instruction/data | Y > > + ---------------------------- > > + | +---- > > + ----+ > > Oh, cool! Looks like this can be used by the hd44780 driver. > > Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt > drivers/auxdisplay/hd44780.c This patchset was from a time when I knew next to nothing about DRM. Now I am just confused on a different level :-) It is on my TODO list to make a mipi-dbi driver that in the future replaces the auxdisplay driver for hd44780. But that TODO list have a growing tendency. It seems that pretending to be co-maintainer on panel/ stuff alone can take up most of my DRM time. I hope Paul will contribute the i8080 support to drm_mipi_dbi, at least he mentioned he planned to work on this. Sam _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
